PHEVS emit more CO2 than diesels, report says

Plug-in hybrid electric vehicles (PHEVs) can consume more fuel and produce more CO2 than diesel models, a research company says.

The Miles Consultancy (TMC), which monitors fuel use for fleets and company car drivers, analysed real-world fuel consumption data on 14 hybrid models and seven plug-in hybrids using its mileage capture and audit system.

These represented 12 different auto manufacturers.

TMC says the PHEVs returned “worryingly-high fuel consumption and emissions” compared to diesel models.

PHEVs in the sample returned on average less than 45.0mpg, compared to their average NEDC figure of 130mpg. The official NEDC test is known to be unsuitable for plug-in hybrids as a large part of the test can usually be carried out under electric-power alone, skewing the average fuel consumption results, Motoring Research reports.

This average fuel use equates to actual CO2 emissions of 168g/km – higher than the real-world emissions of most diesel company cars, TMC says. The diesels’ emissions averaged 159g/km.

“There is a real risk that fleet managers are adopting a PHEV strategy for completely the right reasons but unknowingly actually increasing their fuel bills,” TMC managing director Paul Hollick says.

He says the only beneficiary is the driver paying lower benefit-in-kind tax (fringe benefit tax) on the car. “It is vital that a fleet deploys a mixed fuel strategy, using real world data or support from a company like TMC.

“PHEVs can be a cost-effective choice where drivers cover only moderate mileages; but only if the cars’ batteries are recharged daily. On the evidence of our sample, one has to question whether some PHEVs ever see a charging cable. In a lot of cases, we see PHEVs never being charged, doing longer drives and this is not a good fit for a lot of business car users. A robust PHEV deployment policy is essential.”

The research also revealed that drivers of standard hybrid cars used around 10% less fuel on their day-to-day journeys than drivers of plug-in hybrids. In real-world use, drivers of plug-in hybrids consumed three times more fuel than official figures suggest.

While TMC was compiling its analysis, Belgium’s government announced that it will abolish corporate tax breaks for what it calls ‘fake’ low-emission vehicles such as hybrid cars with limited zero-emissions potential. From 2020, plug-in cars in Belgium will be only granted tax relief on a sliding scale linked to their battery’s storage capacity in relation to the total weight of the vehicle.

United Kingdom company car drivers will encounter a similar tax regime from 2020, when benefit-in-kind tax concessions for electric vehicles, PHEVs and hybrids will be tied to how many miles the car can travel on battery power alone.

After 2019, only pure EVs will attract sizeable tax breaks. Hybrids and PHEVs will increasingly stand or fall on the strength of their total cost of operation in the real world, Hollick says. “Our data sample, though small and therefore not definitive, clearly suggests that PHEVs as a class may struggle to maintain their appeal on a real-world basis.”

As hybrids lose their special tax status and conventional vehicles – especially diesels – face increasing air quality penalties, it will become harder for fleet users to identify cars sitting in the ‘sweet spot’ on running costs, range, taxation and emissions, Hollick says.

“Mobility managers will need access to more complex data models, with comprehensive information on real-world fuel costs and emissions, to identify the best company car contenders in future.”