Laozi

Mercedes-Benz has begun banging the drum over celebs driving its B-class F-cell hydrogen small car, available in Southern California and soon expanding to Northern California.

The German automaker took note earlier in the week that model-turned-actress Diane Kruger is an F-cell motorist. Kruger is known lately for her performance as Marie Antoinette in the movie "Farewell, My Queen." She also starred last year in the movie "Unknown" with January Jones, a leading lady in the "Mad Men" TV series.

"I'm excited to be driving the F-cell.It's environmentally conscious, fun to drive and gets lots of attention on the streets," Kruger says, to which Mercedes-Benz adds that the car has a range of up to 240 miles, a 55 mpg-equivalent, and emits only water vapor.

Honda's also done the celebrity dance for its FCX Clarity hydrogen fuel-cell car, a California-market car. Actress Jamie Lee Curtis was a famous early adopter of the Clarity. And Honda notes that the FCX Clarity will go 240 miles on a tank.

The Test Drive column has evaluated several hydrogen fuel-cell cars over the years.

Honda FCX Clarity production version.

Honda FCX Clarity concept car.

Mercedes-Benz A-class fuel cell prototype.

Chevrolet Equinox fuel-cell prototype.

BMW and GM have enlisted stars to spend time in experimental hydrogen cars. The Mercedes and Honda models are ones you can lease -- if you know the right people, live in the right place (where there are hydrogen filling stations) and have the right situation (including another car to drive so you don't wind up stranded far from a hydrogen station and embarrass the automaker).

But the star-shine isn't the big deal. It's that the companies are beginning to compete on the basis of product attributes -- fuel economy, comfort, refinement -- and that's half a sneeze away from making hydrogen cars mainstream, albeit main in a very narrow, shallow trickle of a stream.

Hydrogen cars, real ones, not science experiments, number only in the dozens. No challenge there to the Camrys and Accords and Altimas of the world.

But they are an enticing solution to pollution. And if real auto company competition begins to catch fire, the cars' development and acceptance could quicken.

Fuel-cell cars are electric cars, but instead of batteries, their fuel cells generate the electricity. The cells pull pressurized hydrogen from the car's tank, pass the hydrogen gas through membranes in the fuel cell and, via chemical reaction akin to magic, produce electricity for power and water as the exhaust emission.

If you're interested in leasing the M-B F-cell, here's where to go.

Honda provides this site for more info on the Clarity and names of dealers offering the fuel-cell car.