The Prius has become damn-near ubiquitous in the decade since Toyota introduced it, and now there are more than 1 million of them on the road. You can bet that number will keep rising right along with fuel prices.

Toyota says cumulative worldwide sales of the Prius hit 1,028,000 last month – when sales jumped 67 percent amid record gas prices – and claims the cars have eased global warming "by producing approximately 4.5 million tons less C02 when compared with gasoline-powered vehicles in the same class."

Despite Toyota's impressive sales figures, hybrids are still just 2.3 percent of the U.S. market. That number is sure to change as consumers ditch their gas-guzzlers. Hybrid sales rose 38 percent last yeareven as overall vehicle sales fell, and with gas prices approaching four bucks a gallon, Toyota's having trouble meeting demand for the Prius.

Priuses (some say the plural is Priora) are getting harder to find in showrooms and buyers are paying more for them. Toyota says domestic inventory is limited by production capacity in Japan, which is shared by the Asian and European markets. The U.S. supply is at its lowest level in two years, according to Bloomberg, and things will only get worse as demand rises.

"This is a special vehicle, and as fuel prices keep rising, it gets more special,'' Toyota spokesman John Hanson told Bloomberg. "Right now, U.S.

customers can get a Prius. Next month or the month after that, it's tough to say.''

With demand rising and supplies falling, Toyota has - surprise! - cut incentives and raised prices. The Prius goes for an average of $25,274, up $869 from a year ago, according to JD Power.

It's hard to believe it now, but the Prius was a hell of gamble when Toyota unveiled in in 1997, when gas was cheap, SUVs ruled the earth and global warming was only beginning to penetrate mainstream consciousness. Today the Prius is the gold standard for eco-friendly vehicles and Toyota has expanded its hybrid line to include the Camry and Highlander.

But the Prius is the cash cow, and Toyota will unveil the next-generation model at the Detroit auto show in January. Auto Observer says it will be bigger, cleaner and more fuel efficient. Toyota also is developing a plug-in version that could be in showrooms by 2010. There's no word on a convertible model.

Photo by Flickr user flickrsquared.