Single piston range extenders such as the technology bought from Swisscom by Polaris Industries have been a failure. By contrast the two cylinder scooter engine range extender used by BMW in the popular i3 was already tooled up and, at a sweet spot of around 30kW for something more than a get-you-home range extender, we have the 3 cylinder version in the BMW i8 and 3 and 4 cylinder versions in production vehicles elsewhere.
Nonetheless, in December 2016, Aquarius Engines, an Israeli startup, said a major European carmaker had agreed to fund further development and road tests of its single-piston generator design, declining to identify the customer. Paris-based PSA, the maker of Peugeot, Citroen and DS cars, confirmed its involvement on a testing basis.
There is a rush for pure electric cars following Tesla proving that 200 mile range is the tipping point and Toyota recently creating a top priority program to develop them run directly by its CEO. Nonetheless, Toyota, global leader in hybrids, has also emphasised in December 2016 that it is gearing up its hybrid program. Expect new range extenders in Toyota cars developed by Toyota because, like BMW, it sees them as a key enabling technology.
See the IDTechEx report, Electric Vehicles Change the World 2017-2037
Top image: Aquarius Motors