8 Key Questions about the BMW i3 Electric Car

By · June 05, 2014

Tom Moloughney's BMW i3

The first range-extended i3 delivered in North America, on May 21, 2014.

Tom Moloughney, long-time EV driver and first owner of a BMW i3 with the range-extender option, answers fundamental questions about the car.

1How is the BMW i3’s range-extending system different from the Chevrolet Volt and Toyota Prius Plug-in Hybrid?

The range extender on the BMW i3 works differently than systems on plug-in hybrids (that to varying degrees sometimes power the wheels from the engine). The rear-wheel-drive i3 is the only pure series plug-in hybrid currently available. The i3’s two- cylinder range-extender engine never mechanically drives its wheels. The Fisker Karma worked this way, but that vehicle is no longer in production.

2Under what conditions does the gas engine come on?

In the United States, the range-extender turns on when the state of charge drops below 6 percent. Unlike the European version, the operator cannot manually turn on the engine to maintain a higher level of charge. In Europe, once the state of charge drops below 75 percent, the range extender can be turned on manually.

BMW eliminated this feature on U.S. models, so the i3 would qualify for the California Air Resources Board’s BEVx designation. While BMW never announced why they chose to eliminate the hold feature in favor of getting the BEVx designation, observers believe BMW took the step in order to get more ZEV credits per REx vehicle sold.

3How does the driving experience change after the gas engine comes on?

So far, I’ve had the opportunity to drive my i3 for about 100 miles in charge sustaining mode. I intentionally didn’t charge it for a couple days so I could fully test the functionality with the range-extender operating. The power is slightly muted. I’d say maybe 85 percent of how it feels with a full charge.

When the range-extender turns on, you cannot hear it at all from inside the car because it initially runs in the lowest of the three power levels. If you continue to drive at speeds higher than 40 miles per hour, it will kick up to the next power level and you can then hear a low hum from inside the car. If you are driving at highway speeds, it will jump up to its highest (28kW) power output, and then you can definitely hear it. It’s nothing that you can’t overcome with the radio.

The REx turns off when you slow down to less than 15 mph, unless your state-of-charge is lower than 3 percent. I’m impressed by how well the little motor can sustain the charge. I’m convinced it can do whatever I need to do, and I will have no problem driving long distances with it running.

On level ground, the car can continuously sustain speeds up to 75 mph for as long as you need to drive. You have plenty of power to pass cars at that speed, and to climb hills that are a few miles long. There really aren’t any mountains in New Jersey where I live, so I haven’t tested driving up long steep inclines, but there is definitely a point where the range extender will not be able to maintain highway speeds.

If you exceed the range extender’s capability, it will slow down to 40 mph. At that speed, it can maintain just about any climb. I will be taking my i3 on a 230-mile trip to Vermont soon. Hopefully I can do some mountain testing there when I do. I haven’t noticed any difference in the handling when the REx running.

4What's the top speed for the i3 before, and after use of gas engine?

The i3’s top speed in electronically governed at 93 mph. It pulls strongly all the way up there, with or without the range extender running. As noted above, it’s just slightly less powerful in charge sustaining mode.

5How did BMW make its decisions about the of the i3’s engine and gas tank?

The i3 was not initially designed to have a range-extender. BMW added the feature after the car was more than a year into development. Perhaps that had something to do with what size motor they could fit, but that is just an educated guess.

The size of the gas tank is another thing entirely. In the United States, the i3 REx has a 1.9-gallon tank, and the European version uses a 2.4-gallon tank. The 1.9-gallon tank for the US was announced only weeks before the i3 launch. The reason for the reduced size is probably tied to the BEVx designation that BMW clearly wanted the car to attain. BMW has not confirmed the reason for the reduced tank size.

One of the qualifications of the BEVx certification is the vehicle’s all-electric range must be greater than its gasoline range. Again, this is speculation, but if the i3’s electric range was certified by CARB at lower than BMW expected, that would explain the need to reduce the range when running on gasoline.

Personally, this isn’t an issue for me. I’ll be using the range-extender only on those rare days when my electric range is just slightly insufficient. It’s a good backup strategy, and allows me to not even think about those times when I’m pushing the limit of the car’s range.

6Should drivers think of the gas engine as a way to extend range to 160 miles—or only as a backup to an 80-mile EV?

I’m not going to tell anyone how to use his or her car. I don’t think there is one simple answer. I believe there will be people that routinely drive their i3 REx 130 to 160 miles and more, and don’t mind filling up frequently when they need to. I can say this about filling up: with such a small tank, you pull in, fill up and pull out of a gas station in about two minutes.

There will be others that see filling up every 50 or 60 miles as too cumbersome. Perhaps the car isn’t the right choice for them. A Volt may be a better PHEV for some people that frequently need to cover hundreds of miles in a day, or live in a mostly mountainous region. For daily driving of less than 150 miles or so, it works great.

7Given the unique i3 system, how does it affect incentives and perks like carpool access?

The i3 REx, like the Volt, Plug-in Prius and other PHEVs qualifies for California’s Green HOV access sticker, which is currently not available. The 40,000 allocated green stickers PHEVs have been exhausted. However, AB 2013 proposes to make 45,000 more stickers available, and is currently headed to the California Senate for vote.

Washington State recently announced the i3 REx would qualify as a zero emission vehicle and therefore gets exempt from sales tax there.

BMW i3 sales in New Jersey were also scheduled to be tax-exempt. But just after BMW began selling the i3 in New Jersey, it was announced that the i3 with range-extender would indeed have to pay sales tax. The BEV i3 doesn’t. That essentially doubles the price of the $3,850 REx option, making it nearly an $8,000 option in New Jersey. That is likely to hurt i3 REx sales in the Garden State.

8Is the i3 REx approach a stopgap measure, or should it be considered a long-term strategy across the EV market?

I believe other manufacturers will adopt the range-extender approach. However I believe it is a short-term measure. (Maybe 10 years?) As battery chemistry advances and energy density improves, electric vehicles will have continually better electric range.

That, combined with increased DC quick charge stations, will make the range-extender unnecessary. Tesla and Nissan are doing the lion’s share of the work getting these fast charge stations installed. It’s about time some of the other carmakers join in.

The i3 is only the first electric vehicle to emerge from the new BMW i brand. More vehicles are already far along in development. It’s my hope that BMW recognizes the need for DCQC infrastructure, and follows Tesla and Nissan. If the combo-cord fast charge standard has any chance of gaining traction in the US, it will be up to BMW to take the lead. It is the only manufacturer currently selling a serious (not a low-volume compliance-only) electric vehicle that uses the combo cord. In my opinion, the proliferation of DC quick charge is absolutely necessary if we are going to get off petroleum, and make a transition to electrified transportation. A small, efficient range-extender like the i3 will work for many people today. It's a great step until battery range grows and more quick charging is installed.


· · 4 years ago

Thanks Tom!

Good writing.

· · 4 years ago

As always, great writeup, Tom! Thanks for your contributions.

I am a little bit surprised that of the "8 key questions" about an electric car, every single one of them was about the gasoline engine. Were there really no key questions about the electric side of things? What about the CFRP body? Driving dynamics? Or do you just feel those have been covered already?

By the way, did you order your car with the DCQC port? I know we have none in the northeast, but that could change. It would be really neat if your trips to VT could include stops at a combination of gas stations and DCQC stations. It could be fun to watch that trip make the slow transition.

· · 4 years ago

Hi Brian. These were the questions asked by plugincars, I didn't make them up. I only answered what was asked. Yes, I have the DCQC option and I even has a chance to use it the other day at BMW headquarters, they have a few of them up there for internal testing. Pretty cool to watch the state of charge go up a percent every 15 seconds or so!

· · 4 years ago

Tom, thanks again for the reply. I figured you didn't make these questions up, I was more curious about the focus on the range extender. Maybe it's a question better directed to the powers that be at plugincars.

I stand corrected on the DCQC in the northeast. I didn't know there was one, but it sounds like it won't be available to the general public. Is that correct?

I'm curious about the performance of the car under more stressful situations, like your long (and hilly) trip to VT. Or during a cold snap in the winter. Knowing you, though, I'm sure that you'll have excellent write-ups on both in due time. In the meantime, I will wait patiently.

Enjoy your new car!

· · 4 years ago

Excellent info; thanks Tom. I agree, I think Quick Chargers are critical to success. I don't know all the pros & cons of CCS (BMW and others use) vs Chademo, but I sure hope they agree on one or some sort of adapter if that's even possible. This article even though almost 1yr old, illustrates the debate. http://www.plugincars.com/why-chademo-death-row-europe-128001.html

· · 4 years ago

Tom: As usual, very interesting and informative report. I wonder how much it would cost to make a Nissan Leaf capable of using ReX? Assuming $3800 or so for the REX, seems to me that essentially doubling the LEAF's range would more than double the number of cars sold... Then having the ability to QC whenever needed, would make EV travel as easy as any other ICE vehicle. By the way, I used Nissan's LEAF as an exsample, could have been other models too. One final thought, wonder how the heater will work in winter?


· · 4 years ago

Can the i3 tank be refilled multiple times on a US car without charging the battery? I live in a hurricane zone and might have to evacuate with a total drive of about 300 miles. Thank You

· · 4 years ago

Tom and All: My wife just 2 days ago bought a BMW i 3. Because she has four small dogs that go everywhere with her, and stay in the car for a couple hours at a stretch when the car is parked, we need for the air conditioner to stay on while the car is parked.
We live in Monterey, CA, so the weather is never very hot or cold. Still, we bought the car with the understanding (from the salesman) that not only could the AC operate while the car is parked, that we could turn the AC on and off using her iphone and BMW remote app.
Does anyone know about how long the AC could be operated in a parked car? I'm guessing it could vary a lot based on outside temperature, state of charge of car battery, etc.
How about operating the range extender engine? Seems like the gas extender engine could operate at low power for hours to keep only the AC going. Your blog says the Range Extender is not manually operated. Is there a way to override that and manually start the engine on leaving the parked car.
Any thoughts/ideas? [ditching the dogs is not an option!]

· · 3 years ago

So living with the i3 for about 4 months I just want to add a few things. The range extender does need to be watched as where you are going and when you will run out of power. Traveling from the High Desert to Cabazon outlet to charge up I did run out of charge and the Aux power did come on. The freeway there moves at 80mph, going up a slight grade into the heavy wind the power did cut out and create a dangerous situation, speed dropped to about 50 mph with the petal floored. This is a problem that they need to address. That said, I absolutely love my I3, I have learned how far and when I need to charge. With a slight change in driving behavior I know where and when I can charge and what the limitations are. Car is exceptional a zipping away at Green lights before anybody else can even step on the gas. Its a absolute blast to drive, quiet and comfortable. The range extender is a backup plan to get you home, it works fine on flat highway speeds, or around town. It is a annoying sound in the background (REX Motor) that I avoid at all costs compared to cruising in silence in this beautiful powerful car. I did lease with the hopes that BMW will come up with longer range in the next generations, however the REX engine is a nice peace of mind to get you home when you don't want to be sitting at a Charging Station 12:00am trying to get home after a long day.

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