Interest from company car drivers put the BMW 330e at the top of the PHEV sales chart in the first nine months of 2020, toppling the Mitsubishi Outlander PHEV. But big premium SUVs are posting disproportionately high sales, with the Range Rover Sport sixth and the Porsche Cayenne 10th in the table as the tax rules punish traditional equivalents. 

“PHEVs are becoming get-out-of-jail-free cards for manufacturers selling heavy, high-CO2-emitting vehicles,” said Berlin-based car market analyst Matthias Schmidt. 

Manufacturers are worried, however, that tales of business drivers giving back PHEVs with unused charging cables are obscuring their true purpose. 

Vauxhall managing director Stephen Norman told Autocar recently: “We haven’t helped ourselves by allowing people to say ‘I bought a hybrid for tax relief and only ever ran it on petrol’. We’re making a rod for our own back.” 

But solutions are coming, such as greater electric range. “The first-generation PHEVs were a little bit short on range, but now we’re introducing a whole raft with a range of around 100km [62 miles], so driving to work Monday to Friday can be emissions-free,” said Daimler CEO Ola Källenius recently. The new Mercedes- Benz GLE 350de has a battery pack of 31.2kWh in capacity, compared with just 13.1kWh for the older Range Rover P400e. 

The weak link, though, is the driver. Incentives sell the car, but if they’re all front-loaded, customers might not bother to plug in, argues the ICCT. It suggests angling incentives toward PHEVs with more power in the electric motor than the engine, meaning they perform worse when not fully charged. 

The ICCT wondered why Americans, not usually the most eco-minded, drive more electric-only miles in their PHEVs than the Europeans and Chinese. Until it realised a shortage of models gave disproportionate weight to the BMW i3 Range Extender, really an electric car with an engine that serves as a generator. 

The problem with both studies was that they were heavily reliant on data from company car drivers, argues the European Automobile Manufacturers’ Association. Much of the data came from fuel cards, and if you’re given free fuel, you’re unlikely to top up using electricity you pay for.