First Drive: Hydrogen-Powered Mazda RX-8 and Premacy

Mazda’s two-car hydrogen fleet doesn’t feel futuristic, and it doesn’t feel like a science project. The RX-8 Hydrogen RE starts immediately with the turn of a key. There’s no waiting for it to warm up. And once the car’s on, there’s no whirring, no clicking, no hiss. There’s nothing to announce the hydrogen being combusted in the 1.3-liter rotary. It merely purrs a soft tremolo whirr.

That’s right: combusted. Instead of developing a fuel cell system, Mazda is running hydrogen through the four-stroke cycle. Doing so in a standard piston engine is difficult because hydrogen is highly combustible -- it's more than ten times more flammable than gasoline. So when hydrogen gets too hot in an engine -- like when it passes valves or a sparkplug -- it combusts prematurely and breaks things.

Likely unbeknownst to Felix Wankel, the rotary engine happens to be uniquely suited for hydrogen duties. Intake and combustion are in two different places, which keeps the hydrogen cool, and the distance between them allows Mazda to fit a larger, more accurate direct fuel injection system. Mazda has been putting rotary mills in U.S. consumers’ hands since the ‘70s, and development is cheaper. Another plus to using a rotary engine in the RX-8: When the hydrogen is all gone, press a button and it switches to gasoline on the fly. It’ll even make the change automatically, should you be too busy bombing down a mountain road to notice the fuel light. To switch back to hydrogen, you have to come to a stop. There’s no danger to going the other way while moving, but Mazda wants gasoline power used as a last resort.