BMW i3 S Versus A Mountain – Can It Summit On Battery Alone?


Let’s charge a BMW i3s and see just how far up a mountain it will travel …

The Fast Lane Car takes the all-new 2018 BMW i3s up to tackle Loveland Pass in Colorado. The Pass sits at about 12,000 feet above sea level. They start out from their office, which is 5,200 feet above sea level.

Will the i3s make it to the top on electric power alone? When and if the range extender (REx) kicks in, will there be any degradation of power? Finally, how much energy can the car recapture on the way back down the mountain, and will the make it back to the starting point?

More Information: 2018 BMW i3s Price Revealed, $3,200 More Than Standard i3

Check This Out: BMW i3 Sport One-Month Review

It’s important to note that the drive will not be an attempt to hypermile, and Eco mode is not used. The idea is to drive the i3s as a normal car, rather than providing an unfair idea of how it might fare by using a fuel-saving feature and going easy on it.

On the way through Boulder, Colorado and up the mountain, the driver fills us in on some important details about the BMW i3 in general, as well as the new i3s.

He begins his trip with 132 miles of range. It’s a 77-mile trip. Give it a watch and see how it all works out.

Keep the conversation going on our Forum. Start a new thread about this article and make your point heard.

Video Description via The Fast Lane Car on YouTube:

Machine vs Mountain: How Far Can We Drive a BMW i3 On A Single Charge up a mountain?

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26 Comments on "BMW i3 S Versus A Mountain – Can It Summit On Battery Alone?"

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Wonfer if the heat was running; 23F is below freezing and that probably contributed to more energy consumption.

I’m sure he was using heating sometime, based on the fact that the windshield was perfectly clear in that cold weather. The batteries don’t put out as much when it’s that cold and the heater draws a ton of power on a irex. . Just use regular Eco Pro and the i3 would have made the summit with no noticeable
degradation in performance. Either way he did over 150 miles trip miles, using a little over a half gallon of fuel. With probably 20ish miles on gas, he probably achieved somewhere close to 125-130 EV miles on his trip, which confirms the stats on my 153MPGe mountain trip. Very impressive considering the factory 97mile EPA EV range rating!

Exactly. You could have pre-conditioned the battery, along with changing it.
This would put the battery temperature up to it’s optimal value. Charging alone, in winter may not get you there. And pre-conditioning would have given him more range.

And it could have been done from the iPhone app.

Comfort and Sport modes use more electricity because the system is ready to deliver more power while you drive. Eco-Pro mode could have been used to drive up the hill like a normal person, you just don’t have “instant jump power”.
But, let’s see the video…

So, just a couple miles on the REX engine at the top. If you’re on a long trip, you’d typically look to putting the car into Eco-Pro mode to stretch out your mpge and charge. He would have made it to the top in Eco-Pro mode.

CARB should allow the BMW i3 to be used like it’s used in Europe.
Allow driver to enable: HOLD MODE.
That way, in city driving you drive the electric motor, and on the highway you drive in REX/Hold mode. On the highway you cannot hear the REX engine running. When you get back to slower speeds or in the city you turn off HOLD mode, and run on pure electric power.

The car is designed for City/EV, Highway/Rex, City/EV long range travel.

I think CARB’s gambit is to force car makers like BMW to build and sell longer range BEVx cars, so that 6% of a 200 to 300 mile range vehicle is more than enough to hold highway speed with a sufficiently sized REX.

I can’t really blame them for that goal.

What I don’t understand is why BMW sells cars with software gimped for the California CARB regulations in non-CARB states when it would be really easy and legal to sell non-gimped cars in places like Colorado.

The range extender test wasn’t long enough. The issue is whether the range extender can continue supplying enough electricity if the battery drops below 6%, 5%, 4%, etc. High altitude reduces the power ICE engines can produce. That is where the first generation REX ran into problems. Since those stories have vanished in recent years, my impression is that the newer i3’s no longer have that problem. It would be good to see him prove it is no longer a problem

6% of a larger battery is more reserve power.
But, there are rumors of an i3 coming with a 160 mile range BEV some time this year.

Current i3 REx’s with the larger 33 kWh battery packs would eventually suffer propulsive power loss in situations in which the REx generator is incapable of providing as much power as is being consumed, but with 6% of 33 kWh being larger than 6% of the original i3’s 22 kWh battery pack, it would take longer for the battery pack’s charge level to drop to where propulsive power is reduced (~3%).

Allowing an i3 REx driver to manually turn on the REx generator while the charge level remains high as is possible in i3 REx’s sold everywhere but in North America would essentially eliminate the propulsive power loss. Fortunately, North American i3 REx drivers can change a parameter value that enables this functionality using a smartphone app communicating with an OBD dongle.

Yup, a test for long enough time to show what it takes to get to 2.5% would be a real test of what it takes to now get power loss. That was always the issue, not whether or not there is less power right when the REX comes on. That was never an issue.

You have a good point about turning on the REX manually. The reason why we never hear stories about REX’s losing power might be because people are simply fixing the problem by enabling EU settings in their NA cars.

The Facebook i3 group thinks the REX can hold charge for anything at or under 70 mph.

This would have been a good chance to confirm that groupthink with video proof.

“The Facebook i3 group thinks the REX can hold charge for anything at or under 70 mph.”

There are a million variables (HVAC, grade, ambient temp, REx software, elevation, etc.), but I have personally cruised at 70 mph for a sufficient number of miles to see that the battery SOC was not declining, and would therefore be able to cruise at 70 mph indefinitely. FWIW, this was with a factory-software ’15 REx, 3 people, rolling slight grades, A/C on, sea level.

More testing would be great, but when it comes down to it, it’s now so easy to code the car via a phone app that it’s basically a no-brainer to do it if you even think you might need HSOC.

I did a similar 5000Ft climb. I charged in Woodland Hills, drove up to 5680 FT Mount Wilson Observatory and back to Ventura County.
Stats: 130 Miles, 4.6 Mi/kWh, 153 MPGe. And so fun through the turns! It is an amazing car…
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Important to realize I was on tight, steep mountain roads, not wide open highway type lanes. And with the cold temp, I’m sure that negatively affected his range. And without the weight of the range extender, and ability to use more of the battery, a BEV i3 would have made his trip!

The REX also suffers from altitude HP loss that you never have to worry about. The 38 hp REX is only 32 HP at 5200 feet, and at 12000 it is down to 24 HP.

Yikes, those are 1960s-70s VW air cooled numbers!

The benefits of a carbon fiber body, reduced weight helps in a number of areas. Smaller electric motor, fewer batteries, smaller REX engine needed.

And at 650cc, probably much smaller than the bug engine.

That is the benefit of REX engines. It can run at peak RPM no matter what your actual engine speed is. With a vintage VW with a 40 hp 1200 engine, you only get that full 40 hp in a relatively narrow RPM range. So most of the time you won’t get anywhere near that HP when you aren’t in that RPM range. And if you let off the gas pedal for a curve or down a hill you aren’t putting horsepower to the wheels at all.

But with a REX that isn’t tied to the RPM of the drivetrain, it can run at peak HP all the time, whether you are slowing down or speeding up or going uphill or downhill, etc. It is always producing the rated HP. Because it can buffer through the battery, it needs less of a motor than direct drive.

On top of that, the REX is computer controlled and can adjust for altitude, where that old VW you have to re-jet and adjust the timing for altitude.

$56K and the guy doesn’t wanna use the gasoline range extender. Go spend $46k and buy a used Model S, and no more gasoline. No more issues making the summit, either. Oh, and you also pocket $10 grand.

You’re welcome.

A lot of people don’t want a big fat a$$ car like a Model S. You’re welcome.

Or buy a used i3 instead of the S and pocket $20. Love how people compare a new car to a used car as though it’s the same thing?

Yea, used i3’s are a great deal over used Tesla’s, it isn’t even close.

This response is for everyone between this and my original comment: it appears the biggest concern to the guy in the video is switching to gasoline. So, my response to that would be to go pure electric. And what pure electric has the greatest rang, performance, and ROI? A used Tesla. Don’t kill the messenger.

Yes, a used i3 is less than a used Tesla. And it still runs on gasoline and won’t make the summit. If you wanna make the summit and sacrifice performance but enjoy a smaller footprint, then buy a used Bolt. The BMW makes no sense financially or in performance. But then again, buying used doesn’t make any sense to a person I’m responding to- which makes no sense to me. Why not let someone else eat 40% depreciation in the first 2 years of a car’s life?

Enjoy your gasoline, new car price, and smaller bank account.

I like this way of range testing a car. I traded in a Prius for the Bolt a couple months ago. My wife drove the Prius exactly like any other car and she would average about 3 mpg less than me, because I considered it an ongoing challenge to beat EPA, which I could. Now, in the Bolt, she drives it as if were “just a car,” and while she uses more electricity than I would use, we still know what to expect when either of us drive it.

To become mainstream, this is how we should present the argument. You shouldn’t start with, “In the ECO Pro mode, you can go…,” but just tell them what it will do in the most normal mode and tell them it will do a bit better in an Eco mode and a bit less in the Sport Mode.