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Are green machines bringing in the green? New data from researcher R.L. Polk & Co. says "yes."

Hybrid sales, the firm reports, were up 38% in 2007 thanks to Toyota's (NYSE: TM) ever-popular Prius and similar models from General Motors (NYSE: GM) and Nissan (Nasdaq: NSANY).

Hybrids -- so-named for their ability to run off of electricity and gasoline -- still comprise just 2.2% of the nation's otherwise shrinking auto market. But savvy investors such as legendary venture capital (VC) firm Kleiner, Perkins, Caulfield and Byers see that as an extraordinary growth opportunity.

Kleiner is teaming with fellow VC RockPort Partners to bring a new electric vehicle to the U.S. from Norway. Called Think City, this battery-powered car from Oslo-based Think Global purports to give drivers 110 miles to the charge.

Eat that, gas guzzlers.

Ford (NYSE: F), especially. The U.S. automaker owned Think for years before selling it back in 2003. Now, Kleiner Perkins partner Ray Lane says, Think City has a chance to be the next Prius. "Our desire is to be selling 30-40-50,000 of these cars in a couple of years," Lane told the Los Angeles Times.

Working in Lane's favor is the very thing that's made investors in oil companies Exxon Mobil (NYSE: XOM) and Chevron (NYSE: CVX) rich: High gas prices. The national average now exceeds $3.50 per gallon.

For its part, Think Global is on to track to expand sales into neighboring Sweden, Denmark, and the U.K. before the end of the year. U.S. shipments are slated to begin in 2009.

Could this be The Next Big Thing for carmakers? Let's not go that far. What we know is that it's efficient (110 miles to the charge), green (all electric, baby), and reasonably priced (below $25,000).

Nevertheless, given what we know of the Prius and the continuing northward march of hybrids, all of that should be more than enough to bring in plenty of leafy green moola. (Ka-ching!)

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Fool contributor Tim Beyers doesn't own shares in any stocks mentioned in this article. You can find Tim's portfolio and his latest blog entry. The Motley Fool's disclosure policy doesn't know if it's easy being green. But it sure enjoys being in the black.