December 24, 2010


BMW's Electric Automobile Revolution (Christian Wüst, 12/24/10, Der Spiegel)

All car manufacturers face the same problem -- even the most modern rechargeable batteries are too expensive, too weak and too heavy to power conventional cars, which are already excessively heavy even without the batteries.

"Integrating electric power into existing vehicle concepts is the wrong way, a dead end," declares Rainer Kurek, head of the Munich-based MVI Group, which develops car bodies and other components for the automotive industry. In his recently published book, Kurek urges vehicle manufacturers to take a completely new approach. "The current hype surrounding electric vehicles," the engineer writes, "is obscuring the fact that today's auto bodies have become far too heavy over the course of the last decades."

A first-series Volkswagen Golf from 1974 weighs 750 kilograms (1,653 pounds). A Golf from today's production series weighs around half a ton more. It's also an entire vehicle class larger than its predecessor, contains a standard eight airbags and can drive into a wall at 64 kilometers per hour (40 miles per hour) without its occupants being seriously injured. Such an accident in the original Golf would have meant certain death.

Technological progress has long meant an inevitable increase in weight. The aluminum auto bodies used in Audi's luxury cars, for example, just barely manage to make up for the weight added by the all-wheel drive system that the brand has made its trademark. Hardly a technical revolution.

Now, though, BMW is attempting to break the cycle. Three years from now, the Munich-based company plans to offer an electric vehicle of a completely different construction type. The project, known as Megacity Vehicle (MCV), won't contain steel or aluminum bodywork. Instead, it will have a light alloy frame in the car floor and a body made of carbon fiber-reinforced polymer (CFRP).

CFRP is a dull black material which has a chemical structure similar to that of diamonds. It is sturdier than steel and weighs less than half as much. The MCV body will be 250 to 300 kilograms (550 to 660 pounds) lighter than that of a conventional electric car of the same size, compensating fully for the additional weight of the batteries.

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Posted by Orrin Judd at December 24, 2010 7:46 AM
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