PHEV models are 61% less efficient in real world use compared to WLTP figures, according to research from Which?.
The independent consumer research firm put 22 PHEV models through a stringent laboratory test, before driving each model 62 miles on the road with their batteries in varying states of charge.
The best performing vehicle in the test was the Toyota Prius, which was 39% less efficient than the official figure of 188.3mpg.
Meanwhile, the BMW X5 plug-in hybrid was the furthest from its official figures, 72% less efficient than WLTP figures suggest.
A previous study revealed that the average PHEV returned 37.2mpg and 193g/km of CO2 due in part to business drivers not charging them regularly.
“While question marks will remain over the environmental impact of PHEVs and the effectiveness of official testing procedures, the greenest optional available is, of course, pure electric vehicles."
Scott Hamilton-Cooper, Director of Sales and Operations for AX
“Pure electric vehicles keep running costs and carbon footprint to a minimum, but some of the better performing PHEVs are still significantly more economical than their petrol or diesel equivalents, so they will be part of the UK car parc for now.”
While PHEVs still out-sell pure electric cars, the gap is starting to close. AX research recently revealed that just a third of UK motorists said they would accept a petrol or diesel vehicle as a replacement for their EV.
The new AX Electric service was launched last month and is available to all EV drivers via AX’s dealer, fleet, insurer and broker partners. AX also offers a direct service for personal customers.