I'm cruising through an industrial district of the port city of Yokohama, Japan - in a Mazda RX-8 sports car. Traffic is slow, but every now and then it opens up and I can gun the motor with satisfying results.
On this cold day, I can see white exhaust foaming around the rear of the car. It's not smoke, but steam. Hydrogen powers this RX-8.
For now, anyway. After a few blocks, I push a button below the headlamp switch. The exhaust note drops maybe an octave to the throaty rumble of a standard RX-8. I've just switched my fuel from compressed hydrogen gas to gasoline.
My drive is taking me down the road from today's petroleum-powered cars to tomorrow's hydrogen-powered vehicles.
I've been invited to test-drive this dual-fuel RX-8 to see how this option to conventional gasoline vehicles stacks up. I'm cruising with a Japanese newspaper reporter, a Mazda engineer and a Mazda PR woman in the four-door RX-8. We're on a short drive from Mazda's Yokohama design center to a hydrogen fueling station and back.
That steam is one reason hydrogen power is seen by some as the planet's savior. Hydrogen-powered fuel cells represent the ultimate in low emissions: nothing but water vapor.
Even setting aside the sky-high cost of the fuel cell itself, though, such vehicles are exceedingly complex. They have a motor, compressor, battery, hydrogen tank or other storage unit as well as the fuel cell.
Moreover, if you drove a fuel cell vehicle today, you would have to plan your driving patterns around the scarce hydrogen fueling stations.
The dual-fuel RX-8 avoids many of those problems. It has a fuel tank and engine. That's it. No major extra components.
Well, not quite. It has two fuel tanks: one for gasoline and one for hydrogen. If you run low on hydrogen, just switch over to gasoline and keep going.
Mazda sees the dual-fuel rotary engine as particularly well suited to a time in the future when the world is shifting from gasoline to hydrogen as a fuel.
"We think the two can live together on the market," says Akihiro Kashiwagi, the program's project manager.
The dual-fuel rotary engine would ease a driver's concerns about finding a hydrogen filling station while the infrastructure for hydrogen gradually is being put in place, he says. It wouldn't solve the chicken-or-egg problem of creating a hydrogen infrastructure, but it could make it manageable.
Also, the dual-fuel RX-8 could fairly easily be built on the same production line as a gasoline-only RX-8. Not true for cars fitted with fuel cells.
I'm driving an updated version of Mazda Motor Corp.'s ninth hydrogen-powered vehicle. The first debuted in 1991. Ford Motor Co. owns 33.4 percent of Mazda.
The RX-8 can drive 62 miles on its 29-gallon tank of hydrogen. It can go another 341 miles on gasoline.
The 15.9-gallon tank of gasoline is the same size and in the same location, under the rear seat, as on the current production RX-8.