High gas prices are pushing an increasing number of U.S. motorists to take a second look at ultra-fuel efficient cars built on hybrid and clean-burn diesel technology.

Today's hybrids are far more sophisticated and user-friendly than the ones sold just a few years ago. Consumers used to have to choose between a fuel efficient car and one that was practical enough for everyday use. Today they can have both.

Hybrid cars pair a traditional internal combustion engine with an electric motor. At high speeds, hybrids rely on the gas engine for power; in stop-and- go traffic, the electric engine gets involved. By switching between gas and electric power sources, hybrid cars can substantially increase fuel efficiency while doing much less damage to the environment.

How much more fuel efficient are hybrids?

The most popular hybrid on the market, the $20,000 Toyota Prius -- now in its second generation -- is capable of delivering over 50 miles-per-gallon. But under normal use, low 40s are the norm. While this is not the promised savings, it is still substantial. And for those people who want to see the United States depend less on foreign oil, this is enough of a fuel savings to accomplish that -- if most Americans bought one.

Two other hybrids currently available are manufactured by Honda: the 45 mile-per-gallon Civic Hybrid and the Insight, a two-passenger hybrid capable of traveling more than 60 miles-per-gallon. Both cars sell for around $20,000. But again, the real-world tests show lower mileage than reported by the manufacturer.

In 2003, Toyota and Honda sold about 40,000 hybrid cars. No other auto manufacturer offered hybrid technology vehicles in 2003.

Growing demand for hybrid vehicles has prompted other major automakers to go after a piece of the growing hybrid market by developing their own hybrids. Industry experts estimate sales of hybrids will reach 177,000 in 2005 and 344,000 by 2008.

A number of automakers are currently planning to introduce full-size sedans and SUVs based on hybrid technology.

While some auto manufacturers are focused on hybrid technology, European manufacturers Volkswagen and Mercedes-Benz also produced ultra-high mileage vehicles that are based on clean-burn diesel technology.

Hybrids are beginning to explode in popularity because they now offer added style, room and power. And the clean-burn, diesel- powered vehicles of today are vastly improved from the diesel vehicles of the 1970's and 1980's.