BMW will launch its new “i” alternative-propulsion sub-brand at the end of 2013 with the i3, a four-seat electric car that promises a range of about 100 miles between charges (and also, possibly, a copyright-infringement lawsuit from chipmaker Intel). Unlike mainstream electric-car makers that repurpose steel production-car unibody structures, the “i” division is starting from the ground up with a lightweight-construction concept.
BMW i3 concept
That said, the i3 isn’t BMW’s first crack at an electric car. The 2009 Mini E and the recently introduced ActiveE are serving as test beds for “project i,” even though both use modified steel unibodies. And unlike the i3, both are lease only, which allows BMW to gather information on the cars’ usage and longevity.
As a result, BMW is learning how to produce an electric car that customers want: one with the range and performance of a gas-powered vehicle. Therefore, the “i” could not be based on a conventional steel unibody. Batteries are heavy. Steel is heavy. Weight is the enemy of range and performance. The whole thing had to be rethought.
So the i3 is based on what BMW calls its LifeDrive architecture. It is basically an evolution of the “skateboard” chassis concept GM pioneered with its 2002 AUTOnomy show car. The Drive module half, made of cast and extruded aluminum components, is the skateboard. It carries a mid-mounted 168-hp electric motor, a single-speed transaxle, a 20-plus-kWh lithium-ion battery pack, and the steering rack, as well as all components associated with its strut-type front and multilink rear suspension. In theory, the board could be driven, albeit dangerously, by adding a few electronic components, a seat, and a steering wheel.
Protecting i3 occupants from the elements is the Life module. It is a 265-pound skeleton of carbon-fiber–reinforced plastic wrapped in thermoplastic body panels (that’s the same stuff used in the front fenders of the 335i coupe), and it is attached to the Drive module via heavy-duty adhesive and five bolts. Because the Drive module carries all the major propulsion components, it easily can be adapted to carry other Life modules, giving the new sub-brand additional diversity in the showroom.
BMW i8 concept
BMW assured us that the basic i3 shape is set, though some steel may have to be added to pass rollover and side-impact crash regulations. Barring any additional, yet to-be-disclosed ferrous material, the Life-Drive chassis has very little steel in it. By limiting structural weight, BMW can get away with a smaller, lighter battery—the same can be said for the electric motor— yet still achieve its target of a 100-mile range. The i3’s radical construction also allowed designers to hit a specific power-to-weight ratio with the 2800-pound car (final output specs are still subject to change).
The “i” brand isn’t just about frugality, though. The i8 plug-in hybrid will follow the i3 by about a year. Made largely of carbon fiber and aluminum, with construction similar to the i3, the i8 will make more power (349 horses) and weigh less (3300 pounds) than the 1-series M. As one BMW engineer puts it, “It is a bad time for the steel business.”
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