Looming emissions controversy for PHEVs

With a ban on the sale of new diesel and petrol vehicles due to come into force in under 10 years, hybrids are becoming an increasingly popular choice. However, recent studies have shown that plug-in hybrids may not be the environmentally friendly alternative they promise to be, with some of the most popular brands found to be up to eight times more polluting than advertised.

Plug-in hybrid electric vehicles (or PHEVs) are petrol cars with a chargeable battery. They have the potential to reduce global greenhouse gas emissions and local air pollution if driven mainly on electricity.

In recognition of these green credentials, while the ban on the sale of new combustion-engine vehicles kicks in from 2030, hybrids have been given a five-year reprieve until 2035. Until recently the government offered incentives for plug-in hybrids under the plug-in car grant, and the vehicles are eligible for a tax break when used as company cars.

In the face of a climate crisis and the recent diesel emissions scandals, PHEVs are clearly an attractive proposition: half a million are expected to be sold in Europe in 2020 alone, with sales in the UK trebling over the last year.

However, new findings warn that PHEVs’ environmental credentials may not be as good as they claim. The study, published by the NGO Transport & Environment (T&E), has found that PHEVs are releasing more CO2 emissions in real-world driving conditions than recorded in official tests. This builds on previous research into the real-world usage of PHEVs by the International Council on Clean Transportation.

Senior director for clean vehicles at T&E, Julia Poliscanova, has gone so far as to label plug-in hybrids “fake electric cars, built for lab tests and tax breaks, not real driving”.

To consumers, this may seem like a familiar pattern: the purchase of diesel vehicles was also incentivised, before the VW scandal broke in 2015 revealing the manufacturer had used a defeat device to cheat official tests – meaning real-world emissions of harmful nitrogen oxide were far higher than approved.

Other diesel manufacturers now face similar allegations. Leigh Day have recently issued proceedings in a claim against Mercedes-Benz and are investigating a claim against Nissan/Renault, alongside VW Group cars including VW, Audi vehicles as well as Porsche.

The T&E study

The findings of the study published by Transport & Environment are stark and should be of concern to motorists and manufacturers alike.

The NGO commissioned testing of the three most popular PHEVs sold in 2019: a BMW X5, a Volvo XC60 and the Mitsubishi Outlander.

On tests conducted with an empty battery, under which the vehicle was powered by the internal combustion engine, it was found:

• The CO2 emissions of the BMW X5 were eight times higher than official values
• The CO2 emissions of the Volvo XC60 and the Mitsubishi Outlander were almost three to four times higher than official values

From the perspective of the utility of PHEVs, of greater concern is the finding that BMW X5 and Volvo XC60 failed to stay in ‘electric vehicle only’ mode under fast acceleration, which, the study concludes, illustrates that for these two vehicles the electric drive is not capable of providing the necessary power which results in the combustion engine coming on sooner.

The study concludes that this “in effect turns around the misleading narrative around PHEVs being good for longer journeys”; in that the PHEVs on sale today “are only suited for short journeys where most of the distance driven is electric. They need to be charged much more frequently that battery electric cars… if they are to keep to their low emission vehicle label”.

Realistic CO2 figures and compliance with EU standards

The study points out that the CO2 official test levels of most PHEVs are reported as less than 50g/km, which is the threshold level needed to unlock super credits in the CO2 car regulations and tax advantages. However, these official test values are premised upon optimistic assumptions on the share of electric kilometres driven by PHEVs, resulting in unrealistically low CO2 values which are unattainable in the real world.

When using real-world PHEV usage data to calculate more realistic official CO2 emissions for the three vehicles being tested, the T&E study found the following for private drivers:

• For the Volvo XC60, the real-world CO2 emissions test value would be 87g/km, against the current official figure of 55g/km
• For the BMW X5, the real-world CO2 emissions test value would be 60g/km, against the current official figure of 41g/km
• For the Mitsubishi Outlander, the real-world CO2 emissions test value would be 64g/km, against the current official figure of 40g/km

The real-world official figures for company cars were found to be even higher.

As a result of the above calculations, the study concludes that for BMW and Volvo (whose official figures are under the 50g/km limit), it is highly unlikely that either manufacturer would meet the CO2 targets with their current PHEV sales if more representative CO2 values were used.

The high real-world CO2 emissions have triggered calls for the removal of the tax subsidies available for PHEV vehicles. T&E-commissioned research found that Germany, France, Italy, Spain and the UK are due to spend EUR 1bn in 2020 subsidising private and corporate PHEV sales, with limited real-world CO2 benefit.

Where to now?

For manufactures and regulators, who are both still dealing with the fallout from dieselgate, the message of the study is clear: “move away from the current “fake electric” technology as soon as possible.”

For consumers, awareness of the issues highlighted by the T&E study is key. Motorists who are thinking about purchasing PHEVs should fully appreciate the likely disparity between the official and real-world CO2 emissions of these vehicles.