Mr. Green Car: BMW i3 is a lightweight, sporty electric
By Allen Penticoff
This will be an introduction to a new car, rather than a road test review, since I don’t yet have access to a BMW i3 to drive. However, if you think about cars as much as I do, you can tell by instinct what it will be like to drive. Besides, this is more a technology report than a review of a car.
The BMW i3 is a small, urban, electric car. What sets it apart from the pack of cars, and electric cars in particular, is that the body and frame are made of carbon fiber reinforced plastic (CFRP). CFRP is similar to glass-reinforced plastic (GRP), or what most of us call fiberglass — the stuff our boats and Corvettes are made of. CFRP is, however, much stronger than fiberglass; it is as strong as steel, but 50 percent lighter in weight.
In design, you aim for a particular strength needed, then build it with CFRP, and you end up with an amazingly light product. But CFRP is difficult to work with and a great deal more expensive than working with steel or aluminum. However, BMW has invested in the technology to mass produce a carbon-fiber vehicle and make it relatively affordable. I’m sure we’ll see more CFRP vehicles; from BMW at first, then from other manufacturers.
Aluminum is important in building something that is lightweight. Airplanes are nearly completely built of aluminum — those that are not carbon-fiber or fiberglass, anyway. CFRP is even 30 percent lighter than aluminum. In the BMW i3, the rear drive module (rear suspension and drivetrain) is composed of aluminum. It has a lightweight and powerful electric motor that produces 170 horsepower, with 184 ft. pounds of torque. With a 450-pound lithium-ion battery pack slung low (no “tunnel”) beneath its flat floor, the battery location adds to its stability, just like the keel of a sailboat.
The BMW i3 has a curb weight of 2,700 pounds, which, for a modern car and an electric in particular, is very lightweight. Combined with all that torque from the electric motor (electric cars have full torque from zero rpm), this little car will be a rocket. Beware, gas-burning hot rods — this little car may embarrass you in a stoplight drag race. Tested acceleration is 0 to 60 mph in just 7.2 seconds.
And being a BMW, it will have great handling. Those who have driven the i3 describe it as “nimble” — which is what I would expect of its size and weight. The interior will be finely finished, and there will be firm, comfortable seats. Driving an electric car is already a pleasure — driving a BMW will make it all the more so.
The i3 has a 22k-Wh battery pack that should provide 80 to 100 miles of real-world warm-weather driving. From my personal experience driving the Volt every day, I can tell you this is more than enough range for normal city driving. If you think you’ll be using more than 35 miles a day of battery power, you would want to get the optional 220-volt/32-amp charging system. If you’ll be going far out of town, you would want the optional 650 cc two-cylinder engine that powers a generator (like the Volt) for extended range. Lastly, BMW offers the optional SAE DC Combo Fast Charging system. These fast chargers, like the Tesla Supercharger at CherryVale Mall, can recharge the i3’s batteries from dead flat to full in 30 minutes, or an 80 percent charge in 20 minutes. More than likely, you arrived with batteries not flat, so the 20-minute charge would be more typical.
The Tesla Superchargers are a network of free charging stations to enable Tesla owners to drive across country on free electricity (after buying an expensive Tesla — why not free “fuel”?). Visit Tesla’s website, www.teslamotors.com/supercharger, to see their map and roll out — there are already 82 such stations across the USA.
The carbon-fiber body of the BMW i3 will have one other benefit of interest to us in northern Illinois. It will not rust! Your paint will not bubble up and lift off. It should do well bouncing off our potholes, as CFRP is very stiff. But, with its small size and spritely handling, you’ll probably enjoy slaloming around the potholes. For now, you can’t have one — they are a California car. So, if you really want one, and are willing to pay the price — have a friend in California buy one for you. If you do, call me and take me for a drive — I’d love to get my hands on one. It would be a great complement to the Volt in our garage.
From the April 2-8, 2014 issue