Mazda rotary engineEnlarge Photo
Fans of Mazda's rotary engines are among the most vociferous advocates you'll find in the automotive world. While some will never understand the appeal of rotary engines, others love their smoothness, stratospheric rev limits, unique noise and the kudos of a Le Mans win, among other things. It's always sad news then when Mazda revives its rotary project, only to cancel it again--it feels like we'll never again see a modern-day RX-7. Or maybe it will--but as part of an electric drivetrain.
Mazda has hinted for some time that its rotary engine would return as part of a range-extended electric vehicle drivetrain. If you're unfamiliar with the concept, that means using the engine to top up the battery pack in an electric vehicle, extending its usable range before recharging. The Chevrolet Volt works on the same principle--but uses a more conventional four-cylinder gasoline engine instead.
Driven by Drive, Mazda's own test vehicle is based on the Mazda 2 subcompact. Normally powered by a 1.5-liter gasoline engine--or a 1.3-liter in some markets--the range-extended '2 swaps that for a 100-horsepower electric motor up front, and a tiny 330-cc, 29-horse rotary engine under the rear cargo space. The rotary doesn't provide any motive force--so there's no crazy all-wheel-drive fun to be had here--instead keeping the car's 440-lb battery pack topped up.
That means double the range--around 300 miles in total, albeit on Japan's city-biased test cycle--without doubling the battery pack, and it keeps all the usual electric car benefits: zero local emissions (in EV mode, naturally), instant torque from low revs (useful in a city-bound vehicle) and incredible smoothness. The rotary is smooth too, which is the main benefit for such a project. Having driven the car, Drive describes it as "almost completely mute" once underway.
The experience echoes our own findings with a very similar rotary-powered, range-extended electric car: Audi's A1 e-tron. Driven on our sister site Green Car Reports, the Audi's similarly-tiny rotary unit produced little more than a faint hum when active, proving little more vibratory or intrusive than a regular, silent electric car. That's a world away from the excitement and noise we're used to with rotary engines, but humbler applications may be just what's needed to keep the rotary alive...