BMW i3 – To REx or Not to REx?

JAN 7 2014 BY TOM MOLOUGHNEY 54

To REx or Not to REx, that is the question many potential i3 buyers are struggling with now

To REx or Not to REx, that is the question many potential i3 buyers are struggling with now

Back in September of 2011, only 6 months after I started my blog, I wrote a post titled “To REx or Not To REx, That is The Question.” At the time, very little was known about the i3, and even less was known about the range extender; other than it would be available as an option and would appear sometime after the initial i3 launch.

The sign at the New York BMW i Born Electric Tour claimed a 100 mile range for the i3. It's looking like the EPA range rating will fall well short of that now.

The sign at the New York BMW i Born Electric Tour claimed a 100 mile range for the i3. It’s looking like the EPA range rating will fall well short of that now.

My conclusion back then was if the BEV i3 had a real 100 mile range I would probably pass on the REx, but if the range was closer to 80 miles and the REx was only about $3,000, then I would probably go for it, providing I didn’t have to wait too long after launch for the REx to be available. As it turned out, my fears about the range were justified. Even though I don’t have proof of the EPA range rating yet, I feel confident by now that the range will be less than I had hoped, and that the i3 will have an EPA range rating that is somewhere in the 80s. I drive a lot and that’s just cutting it too close for me. At 90-95 miles per charge I could probably do it, realizing that after 2 or 3 years the range will likely be in the high 80s anyway. A 100 mile EPA rating would have absolutely eliminated the need for the REx, but no company outside of Tesla is offering that on a real EV (one that is available across the Country). So at $3,850 the REx is a little higher than I would have liked it to be, but it’s not astronomically overpriced, considering the utility value of having it on board and ready when you need it.

Editor’s Note: This post originally appeared on Tom’s BMW i3 blog, which we highly suggest you check out by clicking here.

So after bouncing back and forth a few times, I’ve decided I’ll be getting my i3 with the range extender. After about five years of driving pure electric, I’ll be back to hauling around an ICE. I don’t love the idea, but I’m not hung up on “pure EV” dogma either. The goal is to use less gas and if the range extender allows me to drive on electric the vast majority of the time, yet still have the utility I need on the days I need to drive farther, than the goal is accomplished. The i3 simply won’t have the necessary all electric range that’s necessary for me personally but that doesn’t mean it’s not enough for many others. As you can imagine I’m not alone with the struggle to decide which version of the i3 to get. Now that the i3 is available to order in Europe, and only weeks away from being available in the US, I’m reading posts in the i3 forum and in our i3 Facebook group where others are grappling with the decision of if they should go BEV or REx.

I’ll try to outline the pros and cons here. If you think I miss something please feel free to add your reasoning in the comments section. Here are my top six reasons for and six reasons against the range extender:

Why go for the range extender?

The added utility: Not having to plan out your mileage or look for public chargepoints if you know you’ll be pushing the range on a particular day will be a welcome feature to many people. You won’t have to think twice if your plans change and you need to drive more miles than you planned that day, and on days you know you’ll be driving far you won’t have to use the other family car, borrow a gas car or use a car sharing or rental service. With the exception of extremely long drives (hundreds of miles) that will take you up extended long mountainous routes the i3 with the REx can take you wherever you need to go without worry. Also as the car ages, the battery will lose capacity and your range will shrink. A new i3 with an 85 mile range may only be able to comfortably deliver 75 miles after 3 or 4 years. The REx means the car will always deliver the same utility regardless of how old it is and what shape your battery is in.

What if my battery runs out?

What if my battery runs out?

No range anxiety: There is some over lap with the first reason, but this really is another issue in itself. There is a difference in not using the car one day because you know the range wouldn’t be enough, and miscalculating your total miles because your route had a detour, or your life had a detour that day. It happens. You can plan your day all you want but things come up and you often need to drive farther than you thought you would have to. Usually the extra range you have is enough to get you home, but there are those days where you just come up short and can’t make it. The last few miles you are gripping the steering wheel a little tighter and looking down at your range gauge every minute or so. I’ve been driving electric for nearly 5 years now and I can honestly say these kinds of issues don’t happen often, in fact they are very rare. However when they do happen, it isn’t fun. I can remember walking home at 2am last summer and thinking about how great it would have been to have that little REx motorcycle engine on my ActiveE. On that night, I ran out of charge about a quarter mile from my house. What made it really interesting is I live in a very rural area of New Jersey. There are no streetlights on my street and it’s really pitch dark at 2am. Add to that I saw a bear walking on my lawn a few weeks earlier so as I was walking home I couldn’t help but think of the headline, “EV advocate gets mauled by bear walking home because his electric car ran out of charge.” I don’t know if that is range anxiety or bear anxiety, but I could have really used the REx that night. I know some would say just get an EV with a bigger battery. No matter how big the battery is there could always be occasions when you miscalculate your range or drive farther than you planned and come up short. The range extender virtually eliminates any range anxiety unless you live in an extremely remote area where there aren’t charge points or many gas stations where you drive. If that’s the case, perhaps an EV isn’t the best choice for you right now anyway.

REx Likely to Have Higher Resale Value

REx Likely to Have Higher Resale Value

Resale value: There isn’t a lot of empirical data since modern EVs haven’t been available long enough to really establish how much a pure EV will depreciate as compared to an EV with a range extender. Now that the earliest LEAF and Volt lessees are beginning to return their cars that were on three year leases, I believe in a year or so we can properly gauge if there is much of a difference. I suspect that electric cars with range extenders will fare much better in the second hand market. I know if I were looking to buy a three year old i3 I’d be much more concerned about the condition of the battery if it didn’t have the REx. After three years there will be range degradation, there is no way around it as the battery ages. Will a three year old BEV i3 still have 90% of its original range? How about 85%? We simply don’t have the answer yet. That uncertainty really hurts the value of the car. The potential new owner won’t really know how far it can go until they buy the car and live with it for a while. However if the used i3 has the REx, then the all electric range isn’t nearly as important. The buyer can still do anything they want with the car. They can drive it as far as they want to and the only negative they have is they may use a little more gas than when it was new because of the lower electric range. If it’s a pure BEV they also have to worry about how many more years they have with the car until the range really impacts the cars utility – the REx removes that concern. Of course if you lease the car this isn’t your problem and one of the reasons I recommend leasing if you are in the market for an EV today.

When will this be commonplace?

When will this be commonplace?

Lack of infrastructure: If there were level 2 charging stations in every parking lot, and finding a place to plug in while you work, dine and shop was without hassle, then daily life with a ~80 mile BEV would be simple. If we also had a robust DC quick charge infrastructure then long distance travel would be easy, even if it meant stopping more frequently then you would have to for a gasoline car. However we just aren’t there yet. Outside of certain areas of California and a couple other progressive areas, charging infrastructure is still in its infancy. It’s going to take a while for EV charging to be ubiquitous. I do believe we’ll get there, but not for a while. There will be a lot of growing pains and I believe the number of EV’s sold will greatly outpace the number of public charge points installed. For most people outside of a few select areas, I fear finding available EVSE’s will be very difficult for the foreseeable future.

My ActiveE battery was frequently drained

My ActiveE battery was frequently drained

Damage from frequent deep discharges: This may be a minor concern, but since the REx will turn on at about 6% state of charge, the battery won’t be run down to very deep discharges. There is about 10% buffer when you drain the i3’s battery completely so when the REx turns on the real state of charge is actually about 15%. The buffer is there so you don’t do really deep discharges which would damage the battery. However I can’t help but think if you are a high mileage driver like I am with a BEV i3 and frequently roll into your garage with the state of charge below 5% of the available capacity, the cumulative effect of doing this frequently will have negative effects on the battery. With my MINI-E and ActiveE, there were many times I drained the battery well under 5% and even drove them until they just stopped and wouldn’t go any farther a few times. This isn’t good for the battery, but since these were test cars that would be taken out of service after two or three years there was really no reason to pamper the battery. However if you shell out $45,000 for a new i3, you will want to take good care of your battery, as it’s the most expensive component of the vehicle to replace. Frequent deep discharges can bring on early degradation which will mean less range and perhaps even cause more deep discharges and accelerate the early capacity loss of your pack.

My ActiveE Preconditioning

My ActiveE Preconditioning

Cold weather range degradation: If you live in an area that gets cold during the year this is something you need to be very cognizant of. Even with a sophisticated thermal management system like the i3 has and the ability to precondition the battery and passenger cabin, the range of an electric vehicle is less when it’s cold outside. The combination of the need to use energy to power the cabin heater, the seat heaters, the defroster, etc, plus the fact that the batteries simply cannot store and use the same amount of energy as efficiently as they do when it’s warm conspire to cut into the range. Without having thoroughly tested the i3 in cold conditions, I still feel confident saying you can expect at least a 20% range reduction in temperatures below freezing, and that number could quite possible as much high as 30%. So lets say the i3 gets an EPA range rating of 85 miles per charge. I wouldn’t expect the average driver will get more than 60 – 70 miles per charge when they are driving at or below freezing, and even less as the temperature drops much lower than that. It should be noted that this isn’t permanent range degradation, like I was referring to above. As soon as the temperature rises back up again, so will your range, but that could mean for 3-4 months a year you have to live with an EV will less than 70 miles per charge. With the REx all this means is you may use a little gas, but you won’t have to change your driving style, find secondary roads to your destination so you can drive slower or wear a hat and gloves so you don’t need to use the cabin heater.

Reasons against getting the REx

Do you mind if I smoke?

Do you mind if I smoke?

It’s an electric car! – You don’t want really want to put gas in it do you? The whole reason for going electric is to get away from gas, right? Well there are lots of reasons for going electric while not needing to buy gas anymore is definitely one of the top ones. The way I see it, my goal is to use as little gas as possible. My EVs are mostly powered with electricity generated from my solar array which really makes them as close to true zero emission vehicles as possible. I don’t feel bad if I end up burning 10 or 20 gallons of gas in a year with my REx i3, after all I used to use that much gas every four days when I commuted in my SUV. Still an electric car that burns gas can leave a foul taste in your mouth as the exhaust pipe does when the REx is running

ICE complexity means added maintenance: One of the great aspect of electric cars is their simplicity and
extremely low maintenance. Slap an internal combustion engine as a range extender in there and you just complicate things. Now oil changes, tune-ups, filters, mufflers, etc are all part of ongoing maintenance again, just when the electric car promised to put all that in your past. The only redeeming aspect is since you’ll likely only use the REx occasionally, the maintenance schedule will not be nearly as intensive as it is on a normal ICE car. Still – this is a major drawback in my opinion.

This stuff doesn't belong in an EV

This stuff doesn’t belong in an EV

The added weight of the REx reduces the cars efficiency and performance: The i3 is the most efficient electric vehicle on the road. Everything BMW did while designing it was centered around lower weight and increasing efficiency. The REx adds 265lbs of dead weight to the car, which has to be lugged around everywhere you go. Even if you don’t use the REx for a month at a time, every mile you drive you’ll be carrying it with you. The efficiency will take a hit and you’ll be using slightly more electricity to power the car whenever you drive it. It’s kinda like going hiking and carrying 30 water bottles in your back pack every time you hike, even though you usually only need 1 or 2 of them for 95% of your hikes. Plus, the added weight robs some of the performance. The all electric i3 will go 0-60 in about 7.0 seconds, while the REx i3 will need about 7.7 seconds. Still pretty quick, but if you’re driving a REx i3 and a BEV i3 pulls next to you at a streetlight, kindly decline the invitation for a race.

It takes a little away from the cool futuristic feel of the car: Driving electric is a blast. It’s a different driving experience that most will tell you is actually better than driving ICE. There is also a really cool feeling that you are really driving the future. The ultra silent vibration-less cabin, the instant torque and feeling that you are almost being pulled along by a string instead of the car providing the propulsion really lets you know you are definitely not driving something from a past generation. Add to that the i3’s futuristic architecture, advanced electronic features, extensive use of carbon fiber for the passenger cell, aluminum for the frame and thermoplastic for the outer skin and this is indeed a car of the future that you can drive today. Do you really think an internal combustion engine that’s vibrating and belching pollutants into the air as you drive along really belongs there? Of course it doesn’t.

BMW i3

BMW i3

It will complicate your conversations: I’ve been driving electric for nearly five years now and I still get people asking me about my cars all the time. I can’t go to a car wash without someone asking me about it and often when I return to my car parked in a lot at a shopping center there is someone there looking at it and wanting to ask me about it. With a REx i3 I can no longer say, “Yeah, it’s all electric and I love never buying gas!” like I do now. I see the conversation going something like this:

Them: That’s an interesting car is it electric?
Me: Thanks, yes it is.
Them: Wow! Cool – so it’s all electric?
Me: Well it’s not all electric, but 99% of the time I drive it is all electric. It has a small gas engine that is used to recharge the batteries if I need to drive farther than the electric range will allow.
Them: Oh, so it’s a hybrid. My neighbor has a Prius and loves it.
Me: (Groaning under my breath) No, it’s an electric car with a range extender.
Them: So it’s not like Prius then?
Me: Well it’s not like the old Prius, but there is a new Prius now that is a plug in Hybrid and it’s kinda like that but has a much greater electric range.
Them: So it’s kinda like the plug in Hybrid Prius, but it’s not a hybrid you say?
Me: Have a nice day. (Drives off mumbling)

I’ve driven the i3 a few times now, and the distinctive styling attracts a lot of attention. If you buy an i3 expect a lot of curious people asking you questions about it and the range extender definitely makes explaining the car more difficult.

Cost: The range extender option costs $3,850.00 in the US and that’s a lot of coin. There is also the concern that in some states getting the REx option will then disqualify the car for the zero emission tax exemption. If that is the case, the range extender will end up costing them closer to $7,000 because the sales tax will add another $3,500 or so to the price. However I don’t think this will be the case because I know BMW has been working very hard behind the scenes to get the i3 REx classified as a zero emission vehicle under the CARB BEVx rule. Hopefully we will get clarity on this soon because I know states like NJ, Washington and Georgia (possibly others also) all have exemptions for zero emission vehicles, but not plug in hybrids. Still, even if it only costs the $3,850, that is a significant additional cost.

Equipped With REx

Equipped With REx

Ultimately you have to decide what best suits your needs. I would hate to have someone buy a BEV i3 and then realize they can’t live with the limited range and struggle with worrying about running out of charge. However I also don’t want to give the impression that the BEV i3 wouldn’t work for a lot of people. I happen to drive much more than the average person. I drive between 33,000 and 35,000 miles per year and average around 85 miles per day so for me the REx i3 makes more sense. However as I’ve said, I have lived the past 5 years with pure EVs and really didn’t have too many instances when I wished I had a range extender. Only you know what’s best for you. That reminds me of one of my favorite Dr Seuss quotes:

“You have brains in your head. You have feet in your shoes. You can steer yourself any direction you choose. You’re on your own. And you know what you know. And YOU are the one who’ll decide where to go…”

Editor’s Note: This post originally appeared on Tom’s BMW i3 blog.

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54 Comments on "BMW i3 – To REx or Not to REx?"

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My vote is for no Rex.

This article pretty much took the words out of my mouth. I am really anxious to see what percentage of i3 buyers opt for the range extender. I think it is a well priced option. I can guarantee you if Nissan offered a similar range extender for the Leaf for $3,800 or so, I would have paid the extra to have it. Now that we own a Volt too, I definitely see the beauty in a range extender, for all of the reasons stated above. While I love and prefer to drive in electric mode, I’m not such a die-hard that I really want to plan my life around driving electric and risk getting mauled by a bear.

I always thought the leaf should have a weedeater/chainsaw sized motor option just for heat and emergency battery charging. This would be especially helpful up north.

Indeed. I’ve mentioned something similar before. Even something really tiny and cheap that maybe costs $500 to $1,000 would still be useful. Maybe it couldn’t drive the car solely on gas, but it could extend the overall range if you started it at the beginning of your trip so instead of getting 75 miles range, you might get 100. And if you let it sit for a while and recharge you could go even further. This would be handy for those people that need to charge and can’t for whatever reason. You could use that in place of an L2 station.

Ah, the essence of EREV. Electric when you want it, gas when you need it.

One thing with the i3 and “weed wacker” concept, though, is I don’t think these REx buyers will be able to tap into normal ICE waste heat. Warming the battery with coolant, not watts, and also avoiding the resistence cabin heater are two benefits accrued Volt owners, who don’t want to waste any of their precious 38 miles. This will also hurt the i3 in its EPA test, though not sure how much?

Tom, I thought one of the “Not to REx” reasons would have been the on board 7,400 watt charger, but I suppose that only matters if one expects they’ll be readily available.

Wow, nice all-rounded discussion post!

Tom, I’m afraid that the i3 EPA range might come in even below the 80-85 miles you are now pegging it at. In the Euro cycle it had a range shorter than the Leaf’s and the 2013 Leaf is 84 miles from full charge.

We will soon know…

Not positive, but remember reading that the mode achieving the 84 miles isn’t a default, and therefore isn’t always used during the tests. Someone else has to know, for sure.

I’m surprised that veteran EVers are placing so much value on the EPA range rating. It is super important for the general public and gives a good idea of all around energy consumption. For full range, at least for most people, it is the highway mileage that really matters. The i3 looks as if it will be slightly less efficient than the Leaf on the highway. At 65mph, expect about 65-73 miles of range in decent to good weather and with a newish battery. In a 3 year old battery with 32 degrees, expect about 45-55 miles. 18.8kwh new and the shape of the car is what matters most.

Maybe I missed it, but I’m surprised Tom didn’t mention the fact that CARB has made the REx ineffective because of no mountain mode. To me this is a big negative and also that it can’t be used for cabin heat.

So George, I think I won the bet. I agree with Tom on the Waste heat for the i3 and any 80 mile EREV. Still think it is valid for the Volt and others that are 40 mile or less. The Hold/Mountain mode is more than just about heat and range extension. It is also about efficiency in certain driving conditions. Once you have committed to an EREV you might as well get the good out of it. The Volt probably gives a little more advantage here. For the i3, and others to come, the Rex is just an accessory. Some day they will not be necessary. Today, they are practical solution for a lot (not all) driving needs.

Thanks to Tom for all of his post. He is one of the most level headed pragmatic testers BMW could have.

I am with REx because I want to use this car in my vacation too, and in some location you can not find a gas station, not to mention a plug! I need the range of a Tesla and the i3 can not provide such a thing. In addition I buy my cars for a long time (more then 10 years) and $5k will pay off in a very small amount per month for what this option will offer (a lot of flexibility).

+1, remembering an ICE trip in the White Mountains.

I can already see the “Stage 1” and “Stage 2” upgrade kits. The first including an engine enabler, before reaching 6% SOC. This would help overall efficiency, and reduce the “Absolutely must get gas, THERE” factor. The second being a fuel bladder, that the “tricky” BMW race shops can install, and cage around. Insurers will love this.

It sounds like Tom should give up the love of BMW for a Model S. It would make life easier.

On December 29, 2013, we got our first look at BMW i3 price and ordering guide for the USA. http://insideevs.com/2014-bmw-i3-price-and-ordering-guide-for-us-now-online/ I am in California and did the math. It isn’t pretty. The good, the bad and the ugly, look like this for a California buyer. The base i3 without rex, equipped with leather and the parking pkgs, + license, registration and tax comes to $51,180. The same configuration with Rex comes to $55,415. The Rex model equipped as above plus the addition of some other things you might find useful such as: Navigation, Heated Seats, DC Charger, and Harmon Kardon Audio, brings the total to $60,189.00. I see 700 “Electronauts” saying, “No special gift from Bmw will be substancial enough to make up for the failure to price this car for the market.” BMW would have us believe that eucalyptus veneer and fabrics from recycled this and that are “Cool.” “Just watch the eucalyptus darken as it ages.” Truthfully, I find it austere in the extreme. Just wait until you run through a set of those tires that are only made for this car and only made by one maufacturer. I’m guessing $300 each. Life expectancy for these tires, unknown.… Read more »

Does it really cost $8,905 for tax, registration and tags in CA? For me in NC it would be about $1,300. At least you get to deduct $10,000 in tax credits.

No, it doesn’t cost $8,905, for tax, registration and tags in CA.
California hasn’t figured out how to do that but please don’t give them any ideas.
Your calculations should be:
Add cost of options to base price (with REX or without)
Then add 10%!
(California sales tax, state, county and city, Plus, Department Of Motor Vehicles charges for license, tags and registration. All of this together will add up to a charge of almost exactly,10% of the purchase price of the vehicle)

I would not be in a rush to be the 1st one to order. I suspect BMW will offer a ECOCredit of some sort to move the CRFP. If $3k is being provided for diesels, I would expect the same if not more for the i3 ($3000 I3, $4,000 I3 Rex).

I’ll have to rerun my maths but for CA the discounts are as follows

$7,500 FED
$2,500 CA
$ 0 HOV Lane Access
$4,000 BMW I3 REx ECOCredit
$2,000 General Discount

$16K discount

Would that change your buy / not buy decision?

“Without having thoroughly tested the i3 in cold conditions, I still feel confident saying you can expect at least a 20% range reduction in temperatures below freezing, and that number could quite possibly be as much high as 30%.”

Only a 30% reduction in range would be heaven for my Honda Fit EV. With temps below freezing, I routinely see about a 66% REDUCTION in range.

So far this winter, the winner of the low-range club on myhondafitev.com is 14 miles on a FULL charge… at an ambient temp of 3F.

Thanks as always Tom for your ongoing insights. For 3/4 of the year I live in a large west coat city with very good public transportation and employee provided shuttles. My current 2007 ‘city’ car has 22K miles and gets 26 MPG in the city. I think I am the customer BMW is targeting with the i3. I too struggled with REx or no REx. But have decided to trade by car in and order the REx model for the following reasons. – We are still very early in the ‘EV as primary transport’ thought process and many infrastructure related things must be sorted out – Despite my employer providing on-site Level-2 charging stations, the daily demand is high and many pure EV owners must compete with plug-in hybrid owners for charging times and spaces. Not interested in getting into a row with coworkers over charging. – Weather is still unpredictable and I would feel like a fool with a $50K vehicle in my garage / garage space and unable to use it due to power outage or unexpected change in plans. – Finally, the safety that comes with being in a vehicle versus public transport at night / cold… Read more »

Missing Video Link

Don’t post that stupid fearmonger video.
They take a trip that they know is on the edge of the range. classic stupidity

Range limitation is real, range fear should not be.

I guess I did not see that at all – it is Not common knowledge that battery life drops by half – they stated that they had made the trip easily in normal 20 deg weather and that in 0 deg weather they had used their entire charge for half of the trip.

Good to know for those of us trying to buy a car for climates that (today) fell below 0 deg F, Much less than their experience. I have not seen what percentage drop one can expect from these temps, but it sounds like Drastic is the best you can hope for.

Back to (inefficient) X we go-oo.. as 20 miles from an 80mi BEV will not cover us in winter, ever.

Very good post. I would take one step back, however, from calling the BMW i3 the most efficient electric vehicle on the road until we see the EPA numbers.

Recently, Renault found in their tests that aerodynamics is of more importance than weight in electric car range. While the i3 is light, its aerodynamics are poor. My i-MiEV has the same problem. It weighs less than the i3 but its poor aerodynamics take its toll, especially on the freeway.

Tom,

If it helps your discussions, refer to the REx as a generator. This will help the lay person understand the car much better than confusing it with a Prius. In a Prius, the gas engine moves the car. In an i3, the REx simply generates electricity for the electric motor.

Well written article, thanks for sharing! For me, the REx is a poor solution – my drives are either well within the range of the BEV, or far enough to require 3+ stops for gas (given the tiny gas tank). Like you said, it’s all about what fits a person’s needs, and I am thrilled that BMW is offering real options that let people decide for themselves!

I truly look forward to the all electric highway. I am an advocate/enthusiast/user of solar and electric vehicles. I chose an EREV partly for my driving style but also for my ability to educate and reach a broader audience. The fact is, the general public can understand a hybrid HEV aka Prius or an EREV aka Volt and now i3 Rex easier than they can make the leap to pure BEV. For those who are advanced enough to make the leap, I applaud you!, Many families have at least one commute car that fits the BEV model now. We have to admit that there is a much larger audience that is totally oblivious to this technology and need the security of the current infrastructure. So Tom’s conversation with an EREV gets a postive answer to the questions they have asked before Them: What if you run out of charge? Me: Then I put gas in it just like you do For the transitioning public, this is huge. Yes you give up efficiency for lugging around the extra weight, and yes like Tom, I hate it when the tail pipe come on. But it is well worth it to bring more… Read more »

@Tom,

Great write up!

Please keep us updated when you do get the i3 with REx and let us know how the REx works in the real world…

Thanks!

It’s a somewhat high price but I’m afraid it’s the way to go as long as the fast charge infrastructure sucks as much as it does.

I’ll bet the REx versions average more electric miles than the non REx versions. Not much of a leap here since the groups will be biased this way but that would be the case even without the bias. Most people want a margin for error. This means leaving electrons in the tank for non-REx drivers. Biggest advantage of REx is providing a comfort level to 100% of range. The extra buffer (6%) BMW has engineered in will eat some of this advantage but not all.

A very informative article.
Many thanks.

My questions would be:
How noisy is the RE?

How different is the car to drive using the RE and normally, including top speed?

Is it user controllable, ie can you switch it on if you know that you are on a long run to keep your battery topped up?

Hopefully you and others can help with these!

I’d vote for no REX. Do or do not go EV. Resale value follows a common misconception that people will prefer a PHEV. I don’t believe thats the case. Volt sales are down vs. last year despite a big price drop. LEAF sales up 130% with a big price drop. LEAF has been ahead of Volt sales all 2013 except for the two months it almost didn’t sell in transition to the US. Likewise resale value won’t be good for a PHEV vs an EV either. As battery prices drop and you can potentially get a bigger battery to replace it with, in a car that otherwise takes very low maintenance, EVs may hold their own. REX gets very poor gas mileage. Why would someone want to rely on that when you can get a Prius instead. Frequent deep discharges are MORE likely if you have a REX. Volt owners regularly run their battery out because there’s no bad consequence. Just keep rolling on the ICE. Likewise with a REX there’s no bad consequence to running the battery to 0%. If you don’t have the REX its very bad to run out of juice and you’ll keep a hefty buffer… Read more »

I guess my question would be will the Rex start after driving for an hour or so in -25 to -35°C temps. This is my real world cold winter temps here in the middle of Canada. I will be suffering Rex starting anxiety.

Tom – Welcome to the EREV world 🙂

I won’t go BEV until they make an affordable (to me) 200-mile AER one.

Tom, this is a great analysis, and lots of food for thought.

If you currently drive an BMW ActiveE, I guess you must have considered switching to a Tesla Model S when your electronaut wings get taken away. I know the top end Tesla costs 6 figures, but the lowest cost Tesla is not much above the i3 Rex, and would be an easy adjustment from the ActiveE, and offer all the range you need.

So in your analysis, you do not cover you reasoning for picking an i3 over a Model S, and I wonder if you are willing to share it.

I am familiar with with the driving appeal of all BMWs, and IMHO a model S is more of a “driver’s car” than an i3.

I’m wondering if you order without the REx, can it be retrofitted into the empty space at a later date?

ICE : pump station
EV : charge only
i3 REx : charge + pump station (many more visit)

http://www.telegraph.co.uk/motoring/car-manufacturers/bmw/10440292/BMW-i3-Range-Extender-review.html