Colin Chapman is remembered for many things in the automotive world, but if there's one thing auto journalists have to thank him for, it's an endless stream of column inches dedicated to the weight of cars.

All the calls for lighter vehicles aren't based solely on theory, but a back-catalog of light-weight sports cars that did a great deal with very little.

It's no different these days, only weight is now the enemy of fuel efficiency. Or battery efficiency, if you're Tesla.

The 2012 Tesla Model S may seem portly at up to 4,600 pounds with the largest 85 kWh battery pack, but were it not made of aluminum, the luxury electric sedan would probably weigh a great deal more.

And--thanks to Mr. Chapman--we're well aware that extra weight is detrimental to ride quality, handling, braking, acceleration... and in the case of electric cars, range.

We may not have the best idea of how the Model S drives just yet, but the feedback is certainly positive so far. And with up to 300 miles of range, with the largest battery pack, even the electric car's traditional sticking point has been side-stepped by the Model S. Would it offer that class-leading figure with a heavier, steel body? Unlikely.

Even the Model S base price, at under $50,000, is competitive with gasoline rivals like the Audi A7 Sportback and the BMW 5-Series Gran Turismo. Once, aluminum cars were significantly more expensive than their steel-bodied counterparts.

Of course, aluminum isn't solely responsible for the impressive specification of the Model S--but it could be its secret weapon.


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