A zero-emissions car that runs on hydrogen will become available both in the U.S. and Europe in 2007 with the launch of the BMW Hydrogen 7. Because hydrogen fueling stations are few and far between, it will also run on gasoline. But when it's burning hydrogen, the only thing coming out the tailpipe is the byproduct from burning hydrogen and oxygen: water vapor.

Based on the current BMW 7 Series luxury sport sedan that sells for $76,000 to $130,000, the Hydrogen 7 will have two fuel tanks. A high-pressure hydrogen tank holds 17.6 pounds of hydrogen, good for about 125 miles of driving. The 19.5-gallon gasoline tank adds another 300 miles of driving. The engine is a V12 that produces 260hp, BMW says, and does 0 to 62 mph (100 kph) in 9.5 seconds, with top speed limited to 143 mph for those who call the Autobahn home. In comparison, the gasoline-only V12 760Li produces 438 hp.

BMW says power and engine torque are the same in either hydrogen or gasoline mode; if both tanks have fuel, precedence goes to the zero-tailpipe-emissions hydrogen fuel. While the tailpipe emits no pollutants (nothing beyond water), the process isn't without energy costs in refining, compressing, and transporting the hydrogen.

BMW has not yet announced pricing or exact availability dates. Some of the vehicles may go into limousine fleets where BMW maintains a close link to see how they fare in real-life driving. The vehicles will be nicely equipped, with climate-comfort composite glazing (that is, double-layer side windows), automatic air conditioning, electric seat heating for the driver, front passenger and rear seats; lumbar support; electric seat adjustment with memory function on the front seats, child seat fastenings, Park Distance Control, a rain sensor, exterior and interior mirrors with automatic anti-dazzle, Soft Close Automatic for the doors (they pull themselves shut the last few inches), headlight assistant, navigation, and a high-end entertainment and communication features.

Update, September 18: BMW now says about 100 of these cars will be made available for lease (not sale), and there will be no buyout option at the lease's end. The lease price will be comparable to that of leasing a 12-cylinder, gasoline-engine BMW 760Li, which is about $2,500 per month for a three- or four-year lease on the $120,000 (gasoline-engine) car.

To read more about BMW's high-technology cars, click here.