At 177.7 MPG (Combined Unadjusted) BMW i3 Is Over 5 Times More Efficient Than Comparable Gas Car

1 year ago by Peder Norby 104

You can live and drive powered by sunshine.

You can live and drive powered by sunshine.

Julie and I are fortunate enough to both own and drive BMW i3 Bev’s powered by sunshine. Our BMW i3’s are the principal reason along with Solar PV and a very efficient home, that we are able to live and drive with zero net utility or gasoline cost.

The BMW i3 is rated by the EPA at 177.7 MPG (combined unadjusted – see graphics below), an unbelievable 5.6 times more efficient than the the average new gasoline vehicle which is rated using the same methodology at 24.3 adjusted mpg (or ~31.7 combined unadjusted mpg).

MPG Figures For Most Of Today's EVs - Note The Difference Between Adjust & Unadjusted Values

MPG Figures For Most Of Today’s EVs – Unadjusted Values – For Reference, BMW i3 BEV Is Rated At 124 MPGe On The Adjusted Scale

That directly translates into more wealth for those owners and families who own the car, (or any other electric car) and cleaner air for us all.

Sample Gas Car Rated At 24 MPG (Adjusted) & 31.9 MPG (Unadjusted)

Sample Gas Car Rated At 24 MPG (Adjusted) & 31.69 MPG (Unadjusted) – Categories From Left To Right After Auto (A7) Are As Follows: City/Highway/Combined MPG Adjusted & City/Highway/Combined MPG Unadjusted

*Editor’s note: This post appears on Peder’s blog. Check it out here.

Consider this from a San Diego perspective.

If we as San Diegans achieve 50% electrification of our transportation fleet, we would reduce by 30% the overall emissions in San Diego County. 59% is the total emissions created by our transportation choices. Just as importantly, we would also be creating wealth and economic savings for our families and communities by reducing the cost of transportation fuel.

Our sources of emissions in the City and County of San Diego

Our sources of emissions in the City and County of San Diego

A shift from oil to electricity in our transportation choices enables efficiency gains of up to 700% thus creating economic wealth. As just one example of this, the EPA rates the average new gasoline vehicle at 24.3 mpg ( ~31.7 mpg unadjusted) and the new BMW i3 at 177.7 mpg combined (unadjusted). This is a greater than a 500% improvement in miles traveled using the same amount of energy. The cost savings,wealth generation and improvement in air quality implications if our experience were replicated in an entire city, state or nation is staggering and incalculable.

Most understand the energy savings of a LED bulb versus an incandescent bulb; the same amount of light for 1/5th of the energy used, electric transportation is similar. In any energy or emissions strategy, efficiency is always the highest priority in the loading order and is wealth generating at an equal percentage to the savings.

Using our real world experience gained in the "Driving to Net Zero" Challenge, as compared to the best utility rate and gasoline.

Using our real world experience gained in the “Driving to Net Zero”
Challenge, as compared to the best utility rate and gasoline.

Our highest priority should be reducing and ultimately eliminating the 59% of our emissions in the County of San Diego that are caused by our transportation choices. We can do this by electrifying our transportation choices coupled with equal effort; land use planning that reduces vehicle miles travelled offering greater mobility choices.

As Americans, a long-standing national goal shared by several Presidents of both political parties, has been to reduce and ultimately eliminate our dependency on foreign oil. In 2014, nine millions barrels of oil daily were imported from 75 countries representing 46% of our total oil consumption. We are currently fighting wars involving cost in both money and blood, because oil is still regrettably a strategic concern.

Focusing on getting to 100% renewables in our San Diego electricity grid does zero to contribute in solving this national problem, as our grid contains zero electricity produced with oil.

Focusing on transitioning to electric transportation choices ultimately solves this national problem as the majority of our oil is used and refined to make gasoline.

Looking regionally, are we really willing to dot our backcountry and uproot farmland with hundreds of 50 to 1000+ acre Solar PV power-plants in order to accomplish the goal of getting to 100% renewable energy? (For the record I have supported with concerns, the first several installations as a San Diego County Planning Commissioner.)

Or is the better strategy at least for the next few decades, something less than a 100% renewable energy electricity grid, with a preponderance of distributed renewable energy installations owned by hundreds of thousands of energy entrepreneurs on our existing buildings, parking lots and garages/carports? Solar PV installations that are focused on reducing the four times greater transportation emissions as well as our building emissions.

There are currently 72,000 energy entrepreneurs with solar PV systems in the SDG&E service area. This number is 50x more than existed 10 years ago. In the next 10 years we can easily predict 10x this number. The energy grid is evolving into a more equitable grid whereby if you provide a benefit, you’ll make money, if you are a net user you’ll pay money. Soon there will be millions of energy entrepreneurs on the energy grid. Sounds like what happened to our communications grid doesn’t it?

We have a lot to think about and plan for, unprecedented changes are happening in our transportation and energy sectors. It’s an exciting time of opportunity on all fronts.

Electricity including renewable energy should be thought of first and foremost as a transportation fuel.

That’s both our greatest challenge and our greatest hope. Let’s get to work.

Thank you BMW for making a fantastic car to drive, for enriching our pocket books and for helping clean our air.

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104 responses to "At 177.7 MPG (Combined Unadjusted) BMW i3 Is Over 5 Times More Efficient Than Comparable Gas Car"

  1. Aaron says:

    This should be two articles.

  2. M Hovis says:

    One very interesting twist that I have never seen before is the gasoline cost over 25 years. It has been done over the 8 year warranty of a battery, but it is very interesting to compare the energy source over the 25 year warranty of the solar source. Well done Peder! Look for me to use that one from here forward. =)

    1. Mart says:

      Why use the unadjusted scale? You might as well by using the Japanese cycle…

      1. ggpa says:

        The good news is that he is not using that number in calculations.

  3. ggpa says:

    Good analysis, except
    – gasoline is below $3.50 in many places
    – 177.7mpg in headline is not a useful number. It is intended to allow people to compare apples to oranges, but in reality there are better and more accurate ways to do things, for instance you convert everything to $, which is easy to understand.

    1. SparkEV says:

      You’re right in that one should discuss actual out of pocket $ rather than energy. Hence, I made tables for various EV to quickly look up MPGe$, dollar equivalent MPGe here.

      Gas is below $2.50/gal in many places in San Diego. Still, BMW does quite well at about 55 MPGe$ using EPA figures, bit better than Prius.

      1. sven says:

        Actually, the 2016 Prius Eco is rated 56 mpg combined. Just sayin’. 😉

        1. ggpa says:

          +1, and MPG is real, unlike MPGe, which is a useless fiction

          1. sven says:

            The 2016 Prius ECO reportedly gets phenomenal MPG at steady slower highway speeds:

            78.4 mpg @ 50 mph
            72.1 mpg @ 55 mph
            64.0 mpg @ 60 mph

            It seems like a good choice for people whose daily commute or usual driving patterns are mostly travels at the modest speeds above and don’t involve high-speed interstate driving.

            It’s also been confirmed that the next plug-in Prius will be able to drive in all electric mode with switching on the ICE, and the ICE will be bigger than the ICE in the regular hybrid so that is can more easily recharge the battery.

            1. sven says:

              That should be “without switching on the ICE.”

          2. Elroy says:

            Yeah, the EPA, CARB, and most every other governmental agency understands why they use MPGe. And you somehow now what’s a better rating for all of us to use? Its based on ~33kWh equivalent for a gallon of gas. Because an ICE is much less efficient at converting input energy to the crankshaft than an electric motor. Thus the reason for the high MPGe of course.

            1. ggpa says:

              Elroy, nobody buys electricity in Gallons. It is not a sensible unit of measure to use. It is a simplification that only confuses people like yourself who do not understand the underlying science.

              1. Elroy says:

                GPA..Again, why do you keep bringing up the obvious? Of course people don’t buy electricity by the gallon. So what?? But what you fail to understand is why all the experts (not you) decided to use the ~33.4kWh/GGE equivalent in their rating systems. I’m sorry if you don’t get it like most people do.

                1. ggpa says:

                  It is possible to calculate many ratios. That does not mean they are scientific or useful.

                  For instance, the insights/postings ratio is very close to zero.

                  1. Elroy says:

                    Again the obvious stated. And if it were just your insight, we would truly be at Zero.

                    1. ggpa says:

                      I was referring to the links you post here – they are only true in a specific context, which you do not seem to understand

                    2. Elroy says:

                      The context in which they (the links) are used, and applicable when discussing EVs, is truly something that seems to elude you unfortunately.

                    3. ggpa says:

                      Really, please then explain to me in what context it is possible to convert a gallon of gasoline to 33kWh of electricity?

                  2. Elroy says:

                    Perhaps that is why you are confused…no one here is trying “to convert a gallon of gasoline to 33kWh of electricity.” Nor are we trying to magically make a gallon of gas from electricity. But even if you could, conversion losses would always result in less than a gallon of gas produced, and less than 33.4kWh of electricity produced from burning a gallon of gas. But again, we aren’t trying to convert one fuel to the other. We are trying to compare what various drivetrains do with an equivalent amount of energy when comparing electricity vs gasoline.

                    1. ggpa says:

                      Elroy, I am not confused. You have made a number of wrong assertions and when I point them out, you go into denial and verbal overload.

                      You spoke about “gasoline energy content” but it seems you have no clue what kind of energy it is.

                      You are calling things equivalent when they are not.

                      GGE is an inaccurate, useless shortcut invented for people who do not understand science, but like to pretend they do.

                      And since you finally admit that the conversion cannot happen in real life, it is time to drop the fictional GGE from your vocabulary.

                      People who understand science can compare different drivetrains very accurately, but the answer is a complex one with many variables to explain which means the answer is a bit long for some attention spans.

                    2. Elroy says:

                      -GPA..We understand you dont appove of MPGe and GGE. And another false assertion of yours claiming I dont know the meaning of a content of energy for a gallon of gas in the traditional sense. I could break out the formulas for the reactions that occur and heat release when burning gas….so what. That is far from what is wanted or necessary for a general public cross section to understand. The GGE and MPGe which may not be possible and perfect under your ridiculous scrutiny , is there to help simplify things for the general public. Any moron like you can start questioning and scrutinizing everything that doesnt seem perfect in this world. And in that sense…your logic and arguments are far from perfect to begin with.

                    3. ggpa says:

                      Please stop calling things “equivalent” when they are not. It is very obvious that you are constantly changing the topic. That is pathetic.

                      Right now you are basically asserting what I have said all along. MPGe/GGE are inaccurate simplifications for those who do not understand science.

            2. Pushmi-Pullyu says:

              Elroy said:

              “And you somehow now [sic] what’s a better rating for all of us to use?”

              Gee whiz, Elroy, anyone with even a smidgen of common sense knows how absurd and useless it is to mix two things together in a random ratio and then try to measure the total as if it’s just one of those two things.


              That’s as ridiculous, and useless, as a recipe reading “add two cups of eggs and flour”.

              For PHEVs, miles powered by electricity and miles powered by gasoline should always, always, always be measured and reported separately. There is no rational or useful purpose to add or mix the two together. That only confuses things. That confusion is amply demonstrated by the fallacy underlying all of your arguments here.

          3. speedyice says:

            To explain the MPGe:

            A British thermal unit (BTU) is the energy to heat a pound of water by one degree F.

            A kWh has 3412 BTUs. A gallon of gas has 115000 BTUs. A kWh equivalent in gas is therefore 115000/3412 = 33.7 kWh/G.

            This conversion can be easily used to calc MPGe. For example BMW i3 27kWh/100mi.

            27kWh/100mi = 100mi/27kWh * 33 kWh/G = 124MPGe.

            This number is the amount of energy it takes to get the car down the road in equivalent terms to a gasoline car. The energy use of the car is directly related to it carbon foot print and impact on global warming. Therefore I feel the EPA is using the best measure to describe electric efficiency. I suppose ideally we would just get to the point were 27kWh/100mi would mean something to the average consumer.

            The cost to get the car down the road is a different question, and that’s where spark ev’s chart would come in. You must admit that a chart like that would be hard to understand for the lay man. It would also focus people’s concern on their personal wallet instead of civilization’s greater concerns.

            1. ggpa says:

              Speedy, you write

              “The energy use of the car is directly related to it carbon foot print and impact on global warming.”

              This is NOT a true statement.

              The impact on global warming depends a lot on where the energy comes from.

        2. Mike616 says:

          It’s burning GAS and the i3 isn’t. Zero Gas.
          Zero Carbon.
          Zero Pollution.
          Zero money for Arab terrorists.

          But yes, if you live in apartment and cannot charge that Toyota Prius Aero is a beauty.

      2. Elroy says:

        just do it the way the EPA does it. It is based on simple physics.

        There are 33.4-33.7kWh in a gallon of gas.
        For sake of simplicity, lets just use 33kWh/gallon of fuel.

        Multiply the efficiency
        3.0 mi/kWh x 33kWh= 99MPGe
        4.0 mi/kWh x 33kWh= 132MPGe

        And depending which end of the charger/battery you are measuring it, take away the charging losses.

        10cents/kWh= $3.34 gallon gas energy equivalent

        20cents/kWh= $6.68 gallon gas energy equivalent

        So at 10 cents/kWh we are still paying more than people pay for gas.

        AT 33 cents/kWh+ that some of the public charging stations are charging, you might as well just drive the Prius.

        You can relate cost any way you want in trying to compare ice vs BEVs. However, it is more important to know how efficient the BEVs are in MPGe. Not weighing it against the cost of operating a gas car. Once you know the efficiency, you just have to determine how you electrical costs compare to a sample baseline such as 10 cents/kWh ($3.34 gal). Then just multiply it to figure out where you stand in the cost comparison of operating a BEV. In other words, if you are getting 4x the efficiency of an ICE, but are paying 4x the gallon/energy equiv for electricity, then it is a wash.

        1. ggpa says:

          “It is based on simple physics” LOL, but sadly you seem to have no understanding of Physics or Thermodynamics.

          There is 33kWh of HEAT in a gallon of gas, but when you try and convert that useful energy, a lot of it gets lost.

          Smart people know better than to think heat and electricity is the same thing.

          1. Elroy says:

            If I were talking about heat content, I would have expressed it in BTU not kWh. So if you have the fundamental understanding of thermodynamics that you claim to have, you would have seen that I was expressing energy equivalents in kWh units. Do some reading on the subject, and you can see many others do not relate to “heat content” when discussing MPGe comparisons either. For example, some of the official state website info:


            Furthermore, of course much of the energy is lost in heat when generating electricity from fuel. An even greater amount is lost in transforming the gas to crank horsepower in your ICE. And the of course if you want to be picky, how much energy is lost refining oil, transporting, and pumping it? Is that energy loss calculated in your ICE MPG efficiency? Seriously, when talking about things I am trying to put into simple terms, it not necessary for someone like you trying to make it more complicated than it actually is for comparative purposes.

            1. Elroy says:

              At the bottom of the website table, you will a kWh conversion, and in the last box is clearly says 100kWh = 3.1 GGE
              Which is right a 32kWh/1GGE.

            2. ggpa says:

              “If I were talking about heat content, I would have expressed it in BTU not kWh.”

              You are so outrageously ignorant if you did not know that heat content can also be expressed in kWh. Please read up about the metric system one day, and learn that 1kWh = 3412 BTU.

              BTW, do you know what “equivalent” means?

              Again, there is 33kWh of HEAT in a gallon of gas, which is NOT equivalent to 33kWh of electrical energy stored in a battery.

              Likewise a pound of bullshit is not the same as a pound of gold, but I’ll gladly accept your gold in trade if you think they are equivalent.

              1. Elroy says:

                In case you didn’t understand, that’s the whole point. Why are you trying to argue irrelevant definitions of equivalents, whether it is heat, or energy, etc. For the point of discussion, we use MPGe, whether you like it or not. Of course energy can be converted to heat, etc. And of course there are conversions to and from metric, etc. So what? Do you actually think you are teaching anything useful here? You can eat whatever bullshit you want, but don’t profess that MPGe is so useless and imaginary as if there is not conversion for it, you just admitted about the ability to convert kWh to BTU, pretty obvious actually. No reason for you to get all butt hurt because its too hard for you to understand some predefined and agreed upon unit of efficiency measurement.

                In case you are lost, I will refresh for you:

                Gallon of gas equivalent: 114,000BTU
                7594 kilocalories per liter (Metric!)
                33.41 kWh/gallon!

                Why don’t you read the basis for the EPA rating system:


                “A gallon of gasoline equivalent means the number of kilowatt-hours of electricity, cubic feet of compressed natural gas (CNG), or kilograms of hydrogen that is equal to the energy in a gallon of gasoline”

                So what is it that you don’t understand about “Equal” for these comparison purposes? What were you saying about 33kwh in a battery is not the equivalent energy of 33kWh of gas???

                You should really just agree that these agencies, with all their scientists and engineers might know a little more, and are a hell of a lot more logical than you are.

                1. ggpa says:

                  Again, there is 33kWh of HEAT in a gallon of gas, which is NOT equivalent to 33kWh of electrical energy stored in a battery.

                  FYI, heat content is not the same as electrical energy, or potential energy or kinetic energy.

                  Perhaps one day, someone will teach you.

                  I laughed when I saw you wrote “Gallon of gas equivalent: 114,000BTU”.

                  I hope you enjoy running in circles!!! LOL

                  1. Elroy says:

                    FGPA. Your the idiot that brought up “heat” in the first place. And for what reason?? Just to confuse others? Certainly for nothing productive to this discussion. I thought you could read but here it is again…..

                    “The miles per gallon gasoline equivalent is based on the energy content of gasoline. The energy obtainable from burning one US gallon of gasoline is 115,000 BTU or 33.70 kWh.[3]

                    To convert the mile per gallon rating into other units of distance per unit energy used, the mile per gallon value can be multiplied by one of the following factors to obtain other units:

                    1 MPGe ≈ 1 mile/ per 33.70 kW·h
                    ≈ 8.696 miles/ million BTU
                    ≈ 0.02967 miles/kW·h
                    ≈ 0.04775 km/kW·h
                    ≈ 0.013 km/MJ ”

                    I have no idea what you are arguing for, but at this point if you can’t figure out I was referring to the above information, perhaps you should learn to read before replying any more?

                    1. ggpa says:

                      You mention “energy content of gasoline”. BTW what kind of energy is this?

                      Bottom line is that you keep on introducing long boring, ignorant postings, and all of them are wrong and all of them avoiding the obvious facts that nobody can convert 1 gallon of gasoline to 33kWh of electricity.

                      That means they are not equivalent.

                  2. Elroy says:

                    Kind of funny how other stupid people make the same comparison isn’t it?


                    You might be laughing. But more people are laughing about your arguing about heat from burning gas is not the same as electricity in a battery, etc. Who cares??? It is an established comparison already…33.4kWh/GGE. Is it really that hard for you to accept? Again, I don’t think the EPA cares that you don’t like their rating system…but don’t come here saying a more accurate way to rate it is by price. At least these energy unit equivalents are not volatile like the price of gas is.

                    1. ggpa says:

                      Elroy, the insight to value ratio of your links are close to zero in this argument.

                      You keep on avoiding the fact that Heat, Gasoline and Electricity are different things, which makes it hard to compare ICE to EV consumption.

        2. Johnmb says:

          I’ll take that wash any day… It’s clean air vs dirty fossil fuel… And $1000/yr for my solar rooftop power gives me 8000 miles of bev driving, and ALL my electrical home needs. Those are real world numbers here in Phoenix!

        3. Elroy I take it you have never driven an electric car as your assumptions are way off. I frequently take a 220 mile trip in my EV. That trip takes 48KWh or about 55 KWh with charging losses. Using your $.10/KWh that is $5.50. I have taken the same trip in a Prius and 4.1 gal is the best I have done. So using the best in class car under real world conditions.

        4. Elroy I take it you have never driven an electric car as your assumptions are way off. I frequently take a 220 mile trip in my EV. That trip takes 48KWh or about 55 KWh with charging losses. Using your $.10/KWh that is $5.50. I have taken the same trip in a Prius and 4.1 gal is the best I have done. So using the best in class car under real world conditions I would have to buy the gas at an unheard of $1.34. So the EV wins hands down in the fuel costs. Add in savings of no fluid changes and that EV’S are much more fun and responsive to drive.


    2. Speculawyer says:

      Gas is indeed really cheap right now and it is undoubtedly hurting EVs a bit. But gas won’t stay this cheap. Right now the frackers are just trying not to go bankrupt (and often failing). The tar sands are also money-losers. The supply from the USA, Canada, and other higher-price areas will drop and the prices will go back up.

      Cheap gas generally helps the US economy . . . but there is going to be some nasty fall-out from all the lending of money to the frackers since that is gonna hit the banks & bond funds.

    3. Peder says:

      this is true but the chart was put together in May. In San Diego a historic average over the last several years would support a $3.50 per gallon price but I acknowledge its lower at the moment. Adjust the results accordingly for a price point for your area 🙂

    4. sven says:

      Speaking of apples to oranges, the SLK 350 is an odd choice for a “comparable gas car” It seems the SLK 350 sample car was hand picked for its low gas mileage and use of expensive premium fuel. The Mercedes SLK 350 is a two-seat performance-tuned roadster with the extra weight of a hard-top convertible mechanism and extra bracing in the frame. The SLK 350 goes 0-60 in 5.4 seconds, while the i3 does it in 7.0 seconds. There is also a lower performance more fuel efficient model, the SLK 300, which has a smaller engine and gets 28 mpg (4 mpg more).

      Compare a 2016 Prius Eco with 56 mpg and uses regular gas, with the i3 and the running costs are much closer.

      Also, the 0% cost increase for solar electric is a little misleading, as you would have to replace the inverters at least twice in 25 years.

      1. JakeY says:

        Picking the Prius would not be proper either as it is much slower and not in the same city car segment.

        Probably something like a Mini Cooper S or Fiat 500 Abarth is a better comparison and those are around 30 mpg.

        1. sven says:

          The new Prius is a sporty car, or at least it is being marketed as one! 😀

          1. SparkEV says:

            Prius is antonym for Sporty. Lipstick on pig comes to mind. But their MPG is impressive if true. IF true…

    5. Elroy says:

      Why not disregard efficiency ratings, and just be concerned with $ ratings. Hey, when the EVs cost more to operate than the gas vehicles, I guess that would make the ICE vehicles more desirable in your incredibly ignorant world.(Note: Just returning your childish name calling)

      1. ggpa says:

        LOL … It seems you are confused – If you scroll up you’ll see the EV costs are lower than ICE.

        Now when it comes to MPG (your favorite unit) more is better, but when it comes to $ then lower is better. Please try to remember that.

        1. Elroy says:

          The only thing I will try not remember, is anything you say. EV costs are lower. Lower the better. Wow, lots of useful information there. So when I am at the EVgo Chademo in my LEAF and during a 30 minute charge session pick up 12kWh of energy for $10.00 (83 cents/kWh), is that still cheaper than a gas car? Well, it would get me about 45 miles of driving in my LEAF, and almost 200 miles in a Prius. Oh wow, so many variables when it comes to charging prices, etc. Well as long as I know 10 cents/kWh is okay, I also would know that 83 cents/kWh is 8.3x more expensive then I would ideally want to pay for a charging session.
          Seriously just understand how much you pay for a kWh, and how many miles your car goes on a kWh, and it take 2 seconds to figure out what you relative MPG is . Either based on cost, or efficiency ratings. Any more hopelessly useless information from you that we don’t already know?

          1. ggpa says:

            Bravo, you finally get it “EV costs are lower”. Good job!

            1. Elroy says:

              Wow..such a failure in reading comprehension. I was being sarcastic only in response to your stupidity. I mean I just outlined how it “can” be more expensive to drive 45 miles in my LEAF than 200 miles in a Prius. And you respond by saying “Bravo”, I finally get that EV costs are lower? Its hard to believe you are even being serious.

              1. ggpa says:

                My initial replies were serious, but as I noticed the lack of rigor in your posts, I started laughing, and I have not stopped!!!

                You were wrong on the initial point, and you are running away from that fact with silly diversions.

                Your basic flaw: heat is not the same as electricity. They are not equivalent, even if you can measure both of them in kWh.

                All the superfluous junk you wrote since then does not alter that fact in the least.

                1. Elroy says:

                  I guess that makes two of us that cant stop laughing..
                  You keep harping on the assertion of incompatible energy units, when I gave you all the information of why they came up with MPGe and GGE in the first place. No one asked you for your useless opinion on those ratings. I can assure you a group of high school dropouts didnt devise these comparisons. Its kind of like someone saying they went for a jog and burned x amount of calories. Then some found it easier for the public to understand the calories expressed in watts and “D” cell batteries. Then you come running along screaming….the body calorie usage cant be compared to a D cell battery. Because it isnt exactly the one is producing electricity while the other burning calories. Who cares?? If that is the unit someone puts it in to make it easily comparable..since most people dont understand what a calorie is..then so what. They dont need you to give your useless insight of why it doesnt make perfect sense when the primary objective was to simplify things into terms that people can understand. But then again, perhaps you are too ignorant to understand that simple concept?

                  1. ggpa says:

                    Please stop calling things “equivalent” when they are not. It is very obvious that you are constantly changing the topic. That is pathetic.

      2. martinwinlow says:

        Elroy (et al) – I *really* think you are getting too hung up on the specifics of things, here. MPGe should not be considered a financial measure of why you should buy an EV over an ICE one. It is a ‘comfort’ thing, if you like. I suspect I am not the only car driver in the world who cares more about the bigger picture (oil wars, environment, respiratory diseases etc etc – heck! – just the notion that we are utterly squandering a natural and absolutely finite resource, FCOL!) than what it actually costs me in $ & c (£ & p, in my case) to drive around in/on my EV(s). To me, this is what MPGe represents. It is that simple. No engineering degree required. MW

  4. SparkEV says:

    What is adjusted vs unadjusted? Unadjusted values are approximately what I get with SparkEV, With gas cars, I get very close to EPA MPGe, typically worse. Then what is this adjustment that make EV seem to get lower efficiency than actual?

    1. sven says:

      If I’m not mistaken, unadjusted is CAFE mpg, and adjusted is EPA (window sticker) mpg.

      1. SparkEV says:

        Still doesn’t tell me how adjustment is made other than it makes EV seem worse than it actually is.

        1. sven says:

          A quick Google search came up with this dusty, old EPA technical report:

          “Preliminary Calculation of Fuel Economy Adjustment Factors (Technical Report).”

          And here is a short summary of how EV fuel economy is calculated:

  5. jerryd says:

    This is where the future is people with EV’s making their own fuel, power, at very low cost.

  6. SparkEV says:

    Few things missing from cost analysis.

    First is solar’s upfront cost. If that money is invested in ATT, one would get > 5% dividend (tech average is ~5%). Considering this, “% increase” for solar would be worse than gas / SDGE of 3.5%.

    I was quoted $12K for 3kW system, so that’s also bit higher for solar.

    SDGE charges $0.175/kWh in winter ($0.19/kWh in summer) until about $100/mo. Beyond that, it goes up to about $0.40/kWh. Most people I know without EV are in higher tier, so EV from utility would pay about $0.40/kWh, more than 2X what he quotes.

    SDGE TOU lowest is same as basline rates. For people who have stay at home mom, kids, elderly, or who work at home, TOU is more expensive.

    Even with all that, i3 is better than 318. But it’s not much better than Prius when using SDGE.

    1. Peder says:

      I’ve thought about this investment piece and came to the conclusion that most do not finance their gasoline purchases, and that Solar PV pays for itself as compared to gasoline in less than for 4 years. Since the chart projects 25 years, I decided not to include it.

      However if you do include investment loss, I would do so for only the first four years.

      1. energymatters says:

        I’d note that most gasolina purchases are made with a credit card. This IS finance.

        Granted you don’t pay it off over several years but you would definitely get hit with at least 1-2 months of interest depending on your credit and cash flow situation.

        At typical CC rate of 22% to 27% this can add up.

        1. sven says:

          Or you can pay in full every month the balance on the credit card used to purchase gas, which would be like 0% interest, and an interest-free loan during the grace period.

      2. SparkEV says:

        My point about solar is paying for it upfront vs not having solar at all. Putting the money in dividend fund without solar would be ~5% return. This is regardless of gas car or using SDGE. I don’t consider finance charges as that makes it far more messy.

        Solar ROI depends on usage and investment return for not getting solar. If you include those, solar ROI is far longer; I find it 15+ years. You still come out ahead with solar eventually, and you don’t have uncertainty of gas prices / SDGE. It’s just not as short as many claim.

        You may not live at the house for 15+ years. I think typical home owner moves after 7 years (read it long ago). Solar increase value of the house somewhat, just not sure if that is quatifiably as much as without solar.

        That’s why I think solar that goes with the person would be better; I hope community solar will be as such.

  7. Pete Bauer says:

    Hello Peter

    Thank you very much for buying 2 BMW i3s and also powering it with Solar power.

    Perhaps I should thank you thrice – 2 for 2 BMW i3s and 1 for the Solar power.

  8. kubel says:

    I’m not a vegan or anything, but if you really want to look into potential for greenhouse gas reduction, check out the livestock industry.

    Cutting out half as much meat and dairy intake makes a bigger personal impact on global warming than switching from a gas guzzler to an EV.

    1. Elroy says:

      Ha Ha, then I would wonder how much greenhouse gas was generated in the prehistoric days of dinosaurs, volcanoes and tar pits?

      1. Ambulator says:

        Conditions 65 million (or more!) years ago say very little about what is acceptable today.

        There were a lot of buffalo on the plains one thousand years ago, so I think the climate would stand up to us eating some beef. Personally, I’d rather have chicken.

  9. Elroy a better comparison than comparing the Tesla Roadster to a Prius would be a Corvette or Porshe Turbo. Those cars get 26mpg. So a 220 mile trip would burn 8.5 gal at a gas cost of about $.65/gal. This is WELL below yor calculated $3.38/gal. So yes MPGe is imperfect but I find it a close comparison to what you actually spend. The Roadster is rated at 119 MPGe and you would need a car at about 100 mpg to equal the costs.


    1. Elroy says:

      Hi David, I absolutely agree with you that the EV is very economical when acquiring energy for 10 cents/kWh… But not at 85 cents/kWh. Yes, I have been driving nothing but electric cars for over 2yrs now. I don’t even own a gas car. I have a 2012 LEAF, 2014 Focus, and being shipped as we speak.

      At 10 cents per kWh, it is like getting 100mpg when weighed against the cost of gas , depending of course on the price of gas, and how efficient the gas car is you are using. 16kWh ($1.60) in my LEAF will yield about 60 miles. So yes a Prius would cost almost twice as much for the same distance. (depending on fuel costs/and mpg). But if you are paying 30 cents/kWh, then the savings is not there compared to the Prius.

      If I go to the local $2/hr public charging station station, and get 3.7kWh (less with charging losses). I am paying 54 cents/kWh. So the $2.00 I spent in the LEAF will get me about 13 miles in range. $2.00 in the Prius would probably get me 40 miles in range! Without the need to charge for hours, and having less than 1/5 the range. Hence the need for reasonably priced public charging closer to 10cent/kWh.

      I really don’t see what is so difficult for GGPA to understand.

      A 50MPG Prius will go 50 miles on 33.4 kWh of fuel.

      A 100MPGe BEV will go 100 miles on 33.4 kWh of electrical energy.

      Simple enough, and gives us a sensible system of efficiency rating.

      at 10 cents per kWh…33.4 kWh of electricity would have been $3.34. Right around the price of gas before it started plummeting. As I said, the price of gas fluctuates, and MPG of various gas vehicles varies in comparisons, hence its better to have a dependable MPGe figure in making comparisons. Not uselessly trying to dissect it like GGPA, who doesn’t agree with MPGe. Because of his extensive scientific background, he seems to know what is better for all of us. More than the state agencies, EPA, etc.

      1. ggpa says:

        “Because of his extensive scientific background, he seems to know what is better for all of us. More than the state agencies, EPA, etc.”

        Please do not put words in other people’s mouths.

        You seem to be a devout follower of the GGE/MPGe religion. And your belief has no place for science or facts.

        1. Elroy says:

          To summarize…the system was devised by many experts. You say “it is useless fiction”. Kind of funny, more people find it useful than your worthless insight.
          If anything we know that a 100MPGe BEV will go twice as far on 33.4 kWh of electricity as a 50MPG Prius on 33.4 kWh of energy. Why do you insist on bring up a tangent argument that is irrelevant and useless to our discussion?

          1. ggpa says:

            Reply is below

  10. ggpa says:


    It is funny how you changed your tune several times. I see you carefully avoid stating the type of energy the Prius uses. LOL.

    BTW, heat is not the same as electricity.

    MPGe is a useless fiction that creates the illusion that you can compare apples to oranges. You call things equivalent when they have only one attribute in common, which would be like believing a pound of rocks is equivalent to a pound of gold.

    Believing MPGe is comparable to MPG gives us inaccurate results in many cases. But accuracy is “a tangent argument” for a true believer I assume.

    Good luck with your religion

    1. Elroy says:

      No one cares about the energy being interchangeable to your standards. If you cant get that the ratings give us relatively easy to understand comparisons….then I feel sorry for you. Good luck on your hang ups.

      1. ggpa says:


        My commitment to science is not a hang up. It is a badge of honor that I wear proudly.

    2. JakeY says:

      Wow, I didn’t know the MPGe argument is so heated. The reason why MPGe makes sense is because the MPG number represents a pump to wheel energy efficiency, while the MPGe is the exact analog in terms of pump to wheel. It has nothing to do with heat content, but rather energy content. In scientific analysis it gives a direct number to you can use for the car’s energy consumption.

      The reason converting everything to $ makes no sense at all is because gas and electricity prices vary too much by location and time. Having the MPGe number makes for easy math without the underlying assumptions about energy costs. For the same reason, the EPA doesn’t use $/mi as the primary metric in gasoline cars.

      If you don’t like MPGe, the EPA also provides the equivalent kWh/100 mile number. It’s just MPGe is more familiar to the general public.

      1. ggpa says:

        JakeY, you have one thing right and one thing wrong.

        Right: “EPA also provides the kWh/100 mile number.” – and this is a good number!!!

        Wrong: If you read the stuff above, you could have avoided the obvious mistake in “It has nothing to do with heat content, but rather energy content.”

        Do you know what the C in ICE stands for???

        LOL, if it is not heat, then what kind of energy is it??

        1. Elroy says:

          You seem to be the only one hung up on heat content when nobody asked about it. Lets just say that 33.4kWh=1gal gas= 1 “PILL”

          So without worrying about combustion heat/vs electrical energy, we still know the following:

          BEV is roughly 4x more efficient than the ICE. (80% vs 20%)

          And on one “Pill” the BEV goes about 4x further too. (25 miles vs 100 miles)

          So without even arguing what the Pill is, we know it is useful to know how far each car can go on that unit of energy.

          From the EPA Website:

          “For those vehicles that do not use liquid fuels–such as electric vehicles, plug-in hybrid electric vehicles operating on electricity, and compressed natural gas vehicles– the labels display miles per gallon of gasoline-equivalent (MPGe). Think of this as being similar to MPG, but instead of presenting miles per gallon of the vehicle’s fuel type, it represents the number of miles the vehicle can go using a quantity of fuel with the SAME ENERGY CONTENT AS A GALLON OF GASOLINE.”

          You are so determined to condemn a rating system that was put there simply to make it easier for people to make comparisons.

          And of course we all know that trying to convert a gallon of gas into electrical energy involves huge inefficiencies, just as we know electrical energy can be produced through PV, Hydro, Wind, Geothermal, etc.

          If you haven’t figured out that what you are harping about is irrelevant to this discussion, I truly feel sorry for you.

          1. ggpa says:


            You spend a long time and many, many, many words telling me that you don’t care about my opinions. But the sad fact is, you do care. Which is why you kept on adjusting your theory and posting again and again and again.

            If you start with the wrong foundation, the answer will come out wrong, and that is guaranteed.

            It is kind of pathetic how you kept on adjusting your theory step by step
            1) MPGe is “simple physics”
            2) smart people in the government figured this out
            3) “people find it useful”
            4) MPGe as the EPA does it gives wrong answers for X5, so Elroy will just decide it should be 36, not 59
            5) “no one cares” about objections that it isn’t scientific

            As I said all along “smart people know better than to think heat and electricity is the same thing”.

            1. Elroy says:

              GGPA: I really think your reading skills are pathetic. I will try and summarize for you, since you don’t seem to comprehend much:

              1) “MPGe is “simple physics”
              We are talking about energy content, and how it is utilized to drive an electric car or gas car. Specifically that it involves how far cars can go on 33.4kWh of energy. Whether gas, or electric. And if you think it doesn’t involve physics, I guess you would prefer it to be politics??

              2) “smart people in the government figured this out”
              Yes, I would be very surprised if the people involved in devising this system were not as smart as you think you are.

              3) “people find it useful”
              Of course they do. Why would they take the time to devise a rating system that is not useful? People in this thread already stated it is more useful than your suggestions.

              4) MPGe as the EPA does it gives wrong answers for X5, so Elroy will just decide it should be 36, not 59
              I admitted I do not understand the blended MPG rating. I figured if we knew what the test length was, and then the various amounts of fuel used, it would make sense. I just haven’t seen it yet, or read up on it. Oh, and by the way, talking about going off track…this has nothing to do with our argument above MPGe based on ~33.4kWH being the GGE. Talk about grasping for straws..

              5) “no one cares” about objections that it isn’t scientific.
              I guess you are letting your scientific judgment cloud your practical, common sense thinking.

              As I said all along “smart people know better than to think heat and electricity is the same thing”.

              As I said, your are arguing about something no one asked, and is irrelevant to this discussion. Who cares about the heat/electricity comparison??? So why do you keep bringing it up. “Most Smart People”. I guess that would make most of us dumb, had we objected to that heat/electrical energy comparison, but we didn’t. It something you seem hung up on , that isn’t relevant to this discussion.

              1. ggpa says:

                Hi silly, did you not recognize those 5 points as your work?

                It looks like Elroy spent another hour telling us how he does not care about any of this.


                1. Elroy says:

                  What are you talking about “adjusting my theory”, LOL. I waa merely bringing up various points. They are not part of some imaginary theory.

            2. Elroy says:

              The only thing that is guaranteed is that you have reading comprehension issues:

              1)” MPGe is “simple physics”
              Well yes, we are talking about how far a car will go on 33.4kWh of energy, etc. You would prefer that to involve more politics than physics??

              2) “smart people in the government figured this out”
              Yes, I would be very surprised if they weren’t at least as smart as you.

              3) “people find it useful”
              Of course they do. Why would they waste their time devising the system if it weren’t useful. As people already indicated, they find it more useful than any of your proposals.

              4) MPGe as the EPA does it gives wrong answers for X5, so Elroy will just decide it should be 36, not 59
              I already stated it didn’t make sense to me. I figured if it is a blended figure, I would want to see how much fuel was used, over how many miles. Just because I haven’t researched how the EPA figures the PHEV values out, doesn’t mean they are wrong. They just don’t make sense to me, probably because I haven’t researched it. But this has nothing to do with GGE, or MPGe, which really is a simple/useful rating system.

              5) “no one cares” about objections that it isn’t scientific
              No one cares, when you bring up a heat vs electrical energy argument that isn’t really part of our discussion of MPGe ratings. Its like you keep harping about something that no one asked about.

              As I said all along “smart people know better than to think heat and electricity is the same thing”.
              I guess you think everyone else isn’t smart as you. But in reality, what you profess to have in scientific knowledge, you lack skills in practical knowledge and common sense,.

  11. Pushmi-Pullyu says:

    *Sigh* Why is it that so many PHEV drivers are so determined to redefine the very useful metric “MPG” to make it into a meaningless number?

    The article says:

    “The BMW i3 is rated by the EPA at 177.7 MPG…”

    Okay, so we should blame the EPA for starting this nonsense, but reasonable people should reject that bad meme.

    If we put exactly 1 gallon of gas in a BMW i3 REx, can it then drive 177.7 miles using its gasoline motor for power… or even any distance remotely approaching 177.7 miles? Not only “No”, but “Hell no!!”

    In case anyone needs reminding: The term “MPG” means “Miles Per Gallon”, as in the number of miles a car can be driven when powered by one gallon of gasoline. It does not mean “How many miles I managed to average in my PHEV, using as much battery power as possible and avoiding burning gas as much as possible”… which apparently is what all too many PHEV drivers are trying to use it to mean.

    Reality check: According to, in their road test, the BMW i3 REx got 32.6 MPG. That of course is actual MPG, not pretend MPG.

    1. Elroy says:

      I agree, the PHEV MPG ratings are deceptive. Its like people with Volts programmed into saying they get 1000 Miles on a gallon of gas, without taking into account that the electricity they are driving on represents energy consumption.

      It is truly confusing when I look at the EPA sticker on the X5 40e. It says it gets 24mpg on gas. But 59mpg in the blended mode. But if then says in 100 miles of driving, gas consumption=0, electricity consumption= 59.3 kWh/100 miles. The car only goes about 13 miles. And I would hope on electricity it could get better than 59MPGe.

      I know for the average driver, it is such a strange way of rating the efficiency. Magazine tests have the SUV at 36MPG combined. That’s the number that should be on the EPA sticker, not 59MPG.

    2. 3laine says:

      Totally agreed. Using electricity and gasoline to power your car (often PRIMARILY electricity) and then dividing only be gasoline gallons is ridiculous and misleading. *If* it is to answer a specific question and/or is thoroughly clarified that electricity was the main fuel, then I’m ok with it, but usually it is used to make PHEVs seem more efficient than they really are… which is silly because they are already very efficient, cost-wise. Using a fake number of (electric miles + gas miles) / (gas gallons) just damages plug-in owners credibility.

  12. ModernMarvelFan says:

    The title is very mislead and wrong.

    There is no way it is 5x more efficient.

    The comparison is NOT based on comparable technology. If we using CRFP and narrow tires on ICE cars, they will improve in efficiency as well.

    The easiest way is just use i3 REx’s gas efficency to compare its EV mode.

    117 vs.39

    or 124 vs. 39 or about 3.1x times more efficient.

    Far from 5x.

  13. Bill Howland says:

    30-40 back and forths over that MPGE rating, which to me is only good for comparing electrics to electrics due to the prime mover issue.

    What I’d like to have measured is, what is the ‘mileage and performance’ of the I3 rex when the battery is dead and the heater is on “HI”. Cold weather dwellers where I live would want to know as it is an occurence that would happen every day.

    Performance and mileage degradation has never been tested in the dozens of tests of the I3 to my knowledge. Is it because they both might be horrible that no one ever tests for it?

    Hopefully someone somewhere is curious enough to find out.

    1. ggpa says:

      +1 for “MPGe … which to me is only good for comparing electrics to electrics”

      It is no good for comparing gasoline & electric vehicles, or measuring carbon footprint as folks suggested …

      1. Elroy says:

        Why don’t you explain to all of us the huge energy difference between 33.4kWh of equivalent energy in a gallon of gas and 33.4kWh of electrical energy. Tell us why they can’t be compared? According to the range the cars go relative to their efficiency, it sure seems to correspond to the MPGe ratings. Coincidence??

        So tell us what makes you think they are not comparable?

        1. ggpa says:

          You still ask “So tell us what makes you think they are not comparable?”, after I keep on repeating heat & electricity is not the same thing.

          When you learn algebra they tell you that 5x + 6y is not 11x or 11y or 11xy, you have to keep it as 5x + 6y.

          1. Elroy says:

            For the tenth time, we know they are not the same thing. That is why they use conversion factors. My gosh, are you sure you know what you are talking about?

            So the energy in BTUs E(BTU) is equal to 3412.1416.. times the energy in kilowatt-hour E(kWh):

            E(BTU) = 3412.14163312794 × E(kWh)

            So GGPA, I ask you again, what is the exact difference between the kWh in this conversion vs kWH that can power an electric car?

            1. ggpa says:


              1 Joule of heat is not equivalent to 1 Joule of electricity. Where is the conversion factor for that?

              1. Elroy says:

                Kind of funny they are talking about kWh as a unit of electrical energy when comparing to the British Thermal unit…

                Kilowatt-hour (kWh).The kilowatt-hour is a standard unit of electricity production and consumption. By definition, noting that 1 kilowatt = 1000 watts:

                1 kWh = 3.6 x 10 6 J (exact).

                The relationship between the kWh and the Btu depends upon which “Btu” is used. It is common, although not universal, to use the equivalence:

                1 kWh = 3412 Btu.

                This corresponds to the International Table Btu. [More precisely, 1 kWh = 3412.14 Btu (IT).]

              2. Elroy says:

                Why do you even continue with this pointless argument? It seems the MPGe rating accurately depicts the amount of fuel units that goes in an ICE vs BEV and the range they achieve. For the same amount of fuel/electric energy units, the range corresponds almost identically to the relative efficiency of each drivetrain technology. Without even knowing, or caring about the foundation of the units, you know the units are fairly accurate AND useful, contrary to your own personal opinion.

              3. Elroy says:

                Where do state the E in joules cannot be converted to electrical watts?

                Joules to watts calculation

                The power P in watts (W) is equal to the energy E in joules (J), divided by the time period t in seconds (s):

                P(W) = E(J) / t(s)

                1. ggpa says:

                  Your stubborn ignorance seems endless. Herewith my final response, yet another restatement of the laws of nature, which have not changed in the last few days

                  In science there are units of measure, e.g.

                  – Watt is a rate of energy delivery, or power.
                  – Joule or Wh or BTU all are quantities of energy, any kind of energy.
                  – Gallon or liter are volumes.

                  The flaw in the EPA (and your) argument is that you call the 33kWh of heat energy in a gallon of gasoline equivalent to 33kWh of electrical energy. This is wrong.

                  These forms of energy are not equivalent nor easily interchangable. Which is one reason why most buildings have both electricity and natural gas supplied to them.

                  More examples:
                  – 33kg of rocks is not equivalent to 33kg of gold.
                  – A gallon of milk is not a gallon of juice or a gallon of water or a gallon of gasoline.

                  1. Elroy says:

                    You again have excelled at saying the same old thing that no one cares about. I told you these could be arbitrary X energy units that are used in a context (like the EPA uses) them that works fairly well for comparisons sake.

                    1. Elroy says:

                      Oh and just curious, why do you even think it is necessary to say a Watt is the flow rate of energy, and Wh or kWh is the quantity. (flow over a prescribed time). You act like you are educating us by regurgitating info that most of us already now.

                      Oh, and thank you so much for telling all of us a gallon or liter are volumes. For some reason I thought they were horsepower equivalents. Sheesh…

                    2. ggpa says:

                      Elroy, since you asked …

                      I gave the summary of units because from several of your postings it was clear you had no clue about units, for instance you could not answer even the simplest of questions, like “1 Joule of heat is not equivalent to 1 Joule of electricity. Where is the conversion factor for that?”. Instead you ran in circles and came up with a garbage answer description about “Electrical Watts”.

                      You seem completely ignorant about science, but you pick random words from various sources and cobble them together in a senseless collection and then claim that the errors you make are things “no one cares about”.

                      A quote from wikipedia: “To be termed scientific, a method of inquiry is commonly based on empirical or measurable evidence subject to specific principles of reasoning.”

  14. Bill Howland says:

    Ok ELROY i’ll try my stab at it if anyone is still reading this article:

    My point on MPGE is that the gov’t figure assumes both come from the same starting point, which they do not.


    Most electricity in Hawaii is generated by ICE’s. Some of this juice runs EV’s. So the fair comparison is how much more oil must the utility use to run the EV? You’ve already done a lot of prep work (and paid for it) by the time the juice gets to the connector on the car, but that’s not even considered in the ‘equivalence’ which is being attempted.

    Ice’s are now approaching 50% basic efficiency, even if you don’t have use for the waste heat. If you can make economic use of the heat, the efficiency skyrockets.

    These new (MOSTLY GE) ICE’s are being used more and more for the smaller power plants, mostly oversees.

    The amazing thing to me is people easily understand Hydrogen is not ‘available’ without a lot of prior processing before it gets to the car inlet.

    Why people can’t grasp that electricity has also some ‘prior processing’ before it gets inside the car is a mystery to me.