Lighter Construction with Composites and Lighter Metals

Here is number six in our series looking at fuel economy technologies. If a vehicle can lower its weight it will be able to run with less fuel. There are two main reasons for this. One is that the mechanical friction suffered by the vehicle is proportional to the weight. A heavier vehicle has to spend more fuel fighting more friction. Note that this does not apply to the aerodynamic air resistance friction that begins to really bite at higher speeds. The air resistance does not increase with vehicle weight, assuming the shape of the body stays the same. The other is the investment in kinetic energy to speed up the vehicle. The amount of kinetic energy needed to reach a given speed is proportional to the mass. So to speed up a heavier car, you have to burn more fuel. Then when the car slows down or stops, all of this energy is lost, mainly as heat in the brakes. Heavier car equals greater loss in this way.

The video above explains the Rocky Mountain Institute's Hypercar concept. It is a car made of only fourteen panels of carbon fiber composite. The carbon fiber has half the mass of steel. Because there are only 14 pieces the overall strength of the body is greater than if it were made of steel. The result is a much more fuel efficient vehicle.

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