As car makers contemplate the widening gap between legislation and demand for electric cars, the spotlight has been thrown on to a petrol-electric technology that promises to bridge that gap with fewer of the downsides of plug-in hybrids.
Range-extender (REx) cars package a large battery and a hefty electric motor alongside a small petrol engine, instead of the other way around with most hybrids, in which a large petrol engine dominates.
Advocates of REx technology say that drivers are better incentivised to actually keep the battery topped up, because the electric motor is prioritised over the petrol engine.
With PHEVs coming under fire for emitting more than three times their claimed CO2 in the EU, partly because drivers have less incentive to plug them in, REx cars could prove a better technology to phase out ICE cars by 2035.