Hypermilers are champs at saving gas

A few years ago I was managing an experiment aimed at determining whether it was practical to power cars with hydrogen, instead of gasoline. Most of the cars were small gasoline-engine SUVs which had been modified to burn hydrogen.

Hydrogen, at automotive operating temperatures, is a gas that must be compressed and stored in high-pressure tanks. The tanks are made of carbon fiber. They look a lot like very large scuba tanks. A hydrogen storage system small enough to store aboard a car can only hold enough hydrogen to match the energy content of about four gallons of gasoline.

So, even if a hyd...