The Edison2 prototype can run for 100 miles on a gallon of gas, carry four passengers and meet safety standards. No, it's not a hybrid. For ultra-mileage, batteries are far too heavy. This extremely light vehicle uses a motorcycle-sized gasoline engine for power [source: Lamb].
Hybrids are not the only game in town. Before you buy, consider other ways you could achieve your goals.
Some gasoline-only vehicles are nearly as efficient as hybrids. You could choose a little Smart ForTwo that gets 33 miles per gallon in the city and 41 miles per gallon on the highway. Or a Toyota Yaris (29/36 miles per gallon) [source: Shapley]. Diesel is another alternative. Two clean-diesel cars are among the top 10 most fuel efficient.
All-electric vehicles are about to appear on the market. They do away with the gasoline engine altogether. The Nissan Leaf, for example, can go 100 miles on a single battery charge. All-electrics may be better than hybrid for some drivers.
By simply changing driving habits, you can save fuel with any vehicle, conserving gas and shrinking your carbon footprint in the process. Avoiding rapid acceleration is one technique. Simply driving 65 mph on the highway instead of 75 can increase mileage by 14 percent [source: Reed]
Driving your old car another 20,000 miles might save more emissions than purchasing even the most fuel-efficient new one by sparing the carbon released during the mining, refining of the steel and the manufacturing of the other components. And if reducing emissions is your main goal, consider taking public transportation, carpooling or bicycling.