The last car to be fitted with a rotary engine was the Mazda RX-8 of 2012. The innovative powerplant, also known as a Wankel engine, doesn’t use any pistons – instead, a spinning triangular artefact takes the place of those components.
But the rotary engine could be making a comeback – though not in the way you might expect. Instead of being fitted under the bonnet of a sleek sports car, it will feature as a generator for Toyota’s future series of autonomous electric vehicles.
In this application, the rotary’s inherent downsides – high fuel consumption and short lifespan – are minimised by running at a constant speed, while the advantages of a buttery smooth powertrain and high power output compared to displacement are well utilised. A compact rotary engine would act as a range-extender for the electric Toyotas, allowing them to run for greater distance with fewer expensive battery cells.
“This is a very suitable engine to run a generator because it’s compact and lightweight, with no noise or vibration, and it has very good fuel economy,” said Masahiro Moro, president of Mazda in North America.
The rotary units would see service in Toyota’s upcoming fleet of autonomous delivery vehicles. Capable of being fitted out for a huge variety of applications from pizza delivery to passenger transportation, they’re currently only in the concept stage, and are unlikely to go into production before 2020.
Mazda dropped the rotary engine from its range, having offered various vehicles with the Wankel unit since 1965. The company was unable to bring it in line with emissions regulations without significant reworking.
However, recent Mazda concepts have hinted that the rotary could make a comeback in various applications – most recently, a flagship hybrid sports car dubbed the RX-9.
