Yet again, Mazda has put on hold plans to bring back its rotary engine, this time as a range extender for its first battery-electric vehicle, the MX-30.
More formally known as the Wankel engine, the rotary was once a mainstay of the Japanese brand’s line-up. But the last production model rolled off the line in 2012 when Mazda ended production of its RX-8 sports car.
The company has looked for a new application ever since and last year announced plans to use it to help boost the range of the MX-30 which was limited to about 124 miles per charge. That plan has been scrapped, though Mazda spokesman Masahiro Sakata told Automotive News, “We are still considering using (a) rotary engine as a range extender, but the timing of its introduction is undecided.”
Once leading-edge technology
In the late 1960s and early 1970s, the Wankel was considered a powertrain breakthrough. It was tiny when compared to a conventional internal combustion engine, and required a fraction of the parts. A number of automakers planned to adopt the rotary, at least until a number of weaknesses became apparent.
The technology was not particularly fuel efficient, and it had challenges meeting emissions standards. Worst of all, the seals at the end of its spinning, triangular rotors tended to fail catastrophically. That nearly bankrupted Mazda, while other manufacturers, including General Motors scrubbed plans to bring the Wankel to market. Eventually, the Japanese automaker came up with a solution for the seal issue. But the engine’s weak mileage limited its subsequent use in sports cars like the RX-7 and RX-8.
Even after ending RX-8 production, Mazda continued looking for new applications. And fitting it as range extender seemed ideal. The rotary runs far more efficiently when operated at steady speeds. The idea was to use the engine solely as a generator to provide additional battery once the modest-sized 35.4 kilowatt-hour lithium-ion battery on the MX-30 ran down.
BMW has used a similar strategy with the i3 battery-electric vehicle, the optional i3 REx using a compact 3-cylinder gas engine to boost range.
Latest set of issues
Mazda has not explained why it suddenly reversed course, canceling plans for the extended-range MX-30 using a rotary engine. Reports by Japanese publications, including the Nikkei business daily, indicate the approach would have proved too expensive, among other things, requiring the use of a larger battery in the electric vehicle.
It may also reflect changing perceptions about what BEV buyers actually want. Research has shown that customers in all markets expect longer range than what the MX-30 would have been able to provide solely on batteries. But there also has been less market interest in solutions such as range extenders and plug-in hybrids. BMW plans to end production of the i3 REx this month, the automaker now shifting to longer-range BEVs like the new i3 and iX models.
What other options Mazda might have left for the Wankel engine is uncertain but a more conventional plug-in hybrid may still be in the works, according to the Nikkei. It would feature an even smaller battery pack than the MX-30, offering just enough range for most daily chores and commutes. After the battery runs down, the rotary engine would fire up and take over, allowing the PHEV to continue driving as long as there was fuel in its tank.