In the 1960s, the rotary internal combustion engine promised theoretical fuel savings, and in the 1970s, it confirmed a more rotary character suitable for sports cars. Mazda was the only defender for a long time, but it also abandoned it ten years ago due to the difficult regulation of emissions. Now it is introducing it again as a supplement to extend the range of the electric car.
Mazda approaches electromobility with restraint. Its strategists correctly guessed that battery production would develop slowly, so they settled for a modest capacity and limited range for the first MX-30 model.
At the Brussels Motor Show, they are now presenting an improved version where gasoline will help travel longer distances. However, unlike all the competition, it will not be a piston engine from series production, but a unique rotary engine.
Its advantage is its compact dimensions and low weight, which Mazda has historically used to build small and nimble sports cars. The 1967 Cosmo fit into the tax-advantaged category of small cars. At the same time, with a power of one hundred and ten horses, it reached an unprecedented speed of 185 km/h.
While other manufacturers broke the stick over the Wankel in the seventies, the Japanese took it to an ever higher level with proverbial stubbornness. Chrome-based sprays added durability to the lightweight aluminum parts, added a turbocharger in the 1980s, and won the 24 Hours of LeMans in 1991.
In 2005, they even demonstrated a hydrogen rotary engine. However, this was the music of the future, while the petrol Wankel went to the ice with the introduction of binding CO2 emission limits in 2012. Its return today is all the more paradoxical, as emission targets are further tightened.
The deployment in the MX-30 electric car seems illogical. Its front part is based on the conventional CX-30 type, so a serial production piston four-cylinder would fit under the hood. All plug-in hybrids from Octavia to Mercedes-Benz S-Class have such an arrangement.
At the same time, however, Mazda chose a serial arrangement of the drive, where the internal combustion engine spins exclusively with the generator. That’s why he needs a lower performance. Since the car’s movement is provided by the electric motor, the demand for sharp acceleration will cover the battery for a short time, which will wait until you take off the gas to recharge.
However, Mazda did not have a series engine of reasonably low power available, so it would have to develop something new anyway. That’s why the tried and tested, but significantly improved Wankel got the word. Below average in terms of efficiency, but small and light.
The first published figures prove that all adjustments were focused on reducing the efficiency deficit. The engine has a single rotor, a volume of 830 cubic centimeters and an output of 55 kilowatts at a relatively low 4,700 revolutions. For comparison: the last sports type RX-8 had two rotors, a total volume of 1.2 liters and a power of 170 kilowatts reached up to 8200 revolutions. Direct fuel injection is used for the first time ever in a production Wankel.
It is not yet clear whether Mazda will be able to achieve consumption comparable to a conventional engine and multi-speed transmission. She did not publish further details, and in addition to the Wankel itself, the power transmission will also play against her. The serial hybrid, like the electric car, is not suitable for driving on the highway, when the electric motor with a constant transmission reaches too high a speed.
That it could be more of an electric drive with a little extra practicality is also confirmed by the unusually large battery capacity of 17.8 kilowatt hours, which should be enough for a range of 85 kilometers in the WLTP cycle. At the same time, most plug-in hybrids are only built for fifty kilometers, which is enough to achieve CO2 emissions below 50 g/km.
DC charging is also maintained from the electric car, although its power is limited to 36 kilowatts. With alternating current, the hybrid Mazda can also be charged with three-phase 11 kilowatts. It therefore holds more than half the capacity during an hourly purchase.