But a new trend of "plug-in hybrid" cars combines both. Several car companies, including Toyota, DaimlerChrysler and GM, are working on plug-in hybrids, which have additional batteries that can be charged by plugging the car in. These cars can run on batteries alone for as much as 100 miles between charges. Then they operate as conventional hybrid cars, alternating between the gas engine and electric motor.

Ford unveiled last month its most advanced concept car, the Flexible Series Hybrid Edge, a zero-emissions, plug-in hybrid hydrogen fuel cell vehicle that runs for the first 25 miles on electricity only.

A secretive Texas start-up called EEStor claims to have invented a battery technology -- actually, a fast-charging ceramic "ultracapacitor" -- which provides 10 times the power of conventional batteries at half the cost and without toxic chemicals. The new batteries may show up as early as this year in a new car from Toronto-based Zenn Motor. Because of the EEStor battery technology, the Zenn cars should charge in minutes, rather than hours, and would have many times the range of today's electric cars. Cars running on EEStor batteries may be as powerful as cars running on gasoline, and cheaper and easier to own than gas/electric hybrids. The new battery technology is reportedly applicable to laptops and other consumer devices, too.

All these cars will be desirable to consumers because they're easier to own.

The research revolution