Air Power - 106 mpg and can travel at highway speeds.

Air Powered Car by MDI

A new carmaker has a plan for cheap, environmentally friendly cars to be built all over the country
An air-powered car? It may be available sooner than you think at a price tag that will hardly be a budget buster. The vehicle may not run like a speed racer on back road highways, but developer Zero Pollution Motors is betting consumers will be willing to fork over $20,000 for a vehicle that can motor around all day on nothing but air and a splash of salad oil, alcohol or possibly a pint of gasoline.

On highways, the CAV can cruise at interstate speeds for nearly 800 miles with a small motor that compresses outside air to keep the tank filled. The motor isn't finicky about fuel. It will burn gasoline or diesel as well as biodiesel, ethanol or vegetable oil.
This car leaves the highest-mpg vehicles you can buy right now in the dust. Even if it used only regular gasoline, the air car would average 106 mpg, more than double today's fuel sipping champ, the Toyota Prius. The air tank also can be refilled when it's not in use by being plugged into a wall socket and recharged with electricity as the motor compresses air. More