How to save fuel and reduce injuries in automobiles.

Increased fuel economy and reduced injuries have been portrayed as incompatible goals, based on the false assumption that vehicle weight is the determining factor in both. Physics predicts that size and velocity, not weight, are the primary factors affecting crash forces, while increased weight or increased velocity consumes more fuel. Analysis of fatal injury rates, injury costs, and fuel use relation to vehicle weight, vehicle size, and engine horsepower confirms that weight is of minimal importance in injury severity compared to the other two factors. Fuel use is a function of weight and horsepower. Injuries and fuel use can be reduced by reducing vehicle horsepower without changing vehicle size.