Body technologies such as weight savings are particularly important because, as new propulsion technologies such as fuel cells are developed this century, the weight and drag of the body will continue to be important factors in the total amount of energy needed to propel the car.

Not only does less weight mean that less energy is needed to accelerate the car up to speed, but reducing body weight means that the motors and batteries can be made smaller for still further weight savings.

The first step in reducing weight is to make the overall size of the car smaller. Both the Insight and Prius are relatively small cars, though the Insight's two seat format allows it to be made a little smaller.

While the Prius has a fairly conventional steel body, the Insight's body is made of an aluminum alloy. Aluminum makes for a body that is roughly 40% lighter than the same sized body would be if made of steel, helping to improve the Insight's energy efficiency, while also increasing its rigidity.

Another interesting advantage of aluminum is that while it will corrode, it doesn't degrade nearly as quickly as steel rusts. This is because aluminum forms an aluminum oxide barrier that prevents further corrosion, while steel which starts to flake thus continuing further corrosion. Obviously the more quickly a vehicles deteriorates, the sooner it will need to be disposed of. There are now a number of all-aluminum cars on the market, including the Honda Insight, Audi A2, Audi A8, and Chrysler Prowler.

The Insight's aluminum alloy body