for hydrogen-powered cars that's now running from Portland, Maine to Santa Monica, California. The four BMWs in the tour are powered by internal combustion engines running hydrogen fuel (two of these can also run on gasoline), while the other vehicles all use fuel-cell driven electric motors. The latter were developed by Daimler, GM, Honda, Hyundai-Kia, Nissan, Toyota, and Volkswagen.
Now we've covered development of the Hydrogen 7 on this Website recently, and I've followed the technology since it was first announced by BMW early this decade—so driving the car was not so much a revelation but reaffirmed the engineering development that went into the car. As a matter of fact, if you weren't told the car was hydrogen powered, a driver would have no way to tell from its performance, only by the gauges on the dash—thus, good design by being transparent to the user.
Those gauges in bi-fuel version I drove tell how much gas (liters) and liquid hydrogen (kg) are in their respective tanks. The H2 tank holds 8 kg of liquid (with some room left for gaseous fuel) at 3-5 bar (the BMW folk say a champagne bottle is at 7 bar). Range on hydrogen is about 125 miles. Simply pushing an "H2" button on the steering wheel alternates between the two fuel supplies seamlessly, even at highway speed. Under the hood, the only sign of the hydrogen fuel is an insulated and foil-wrapped fuel line (along with the word "hydrogen" on the engine cover).
How clean does the car run? Well, I stuck my nose near the tailpipe while the car was idling and detected no odor—and putting my hands in the H2O exhaust felt like the warm steam stream coming from a room medical vaporizer. BMW says testing done at the U.S. Argonne National Laboratory showed the hydrogen-only version of the car actually cleaned the air—and other studies found the water emitted was safe for drinking.
Last week I was lucky enough to cop a drive in the BMW Hydrogen 7 during the 
