A European lobby group claims the green credentials of plug-in hybrid cars in real world driving conditions are not are not what car companies claim they are. It says many top-selling plug-ins default to petrol use more quickly than they should.

With sales of plug-in hybrid cars continuing to increase across Europe, the European umbrella group for non-government organisations pressing for sustainable transport - Transport and Environment -  says tests on the newest PHEV's confirm they pollute far more than car makers claim - even when starting on a full battery.

Transport and Environment says emissions have been analysed in Europe, the United States and China. Real world factors included how often the battery was charged (in Germany, one of the biggest markets for plug-in's owners reported charging three out of every four days), quick acceleration, the use of heaters and air conditioning units and other factors that increase the use of the petrol engine. Many of these engines are of a 2.0 litre petrol capacity, or bigger.

T and E  says three of the most popular plug-ins in 2020 all emitted more CO2 than advertised, when tested in the real world, just as research on older PHEVs has shown.

The group says governments should end the purchase subsidies and generous tax breaks for plug-in hybrids that "are fuelling another emissions scandal".

The Mitsubishi Outlander is a popular plug-in choice in Ireland.

It says the BMW X5, Volvo XC60 and Mitsubishi Outlander emitted 28-89% more CO2 than advertised when tested by Emissions Analytics on a fully charged battery in optimal conditions. On an empty battery, they emitted three to eight times more than official values, says the group.

However, the EA study shows that if the battery on a plug-in is always charged and the car does only short journeys almost zero emissions are possible.

The problem appears to be the length of time the car is falling back on the power of a large petrol engine in real-world conditions.

Emissions Analytics, one of the world's leading independent emissions research companies, says that "once you introduce real-world driver behaviour in terms of trip mixes and charging up of the battery between trips, it becomes clear that there is a significant problem.  Real-world CO2 emissions are as high as 299g/km in average urban driving if you never charge the battery up.  At the other extreme, if you always charge up the battery and only ever take short journeys, CO2 emissions will be almost zero.  In other words, there are orders of magnitude of difference between the best and worse cases." 

EA says the proportion of kilometres travelled on the battery is called the "utility factor" (UF). 

"If we compare the average European real-world tailpipe emissions of 182g/km from a PHEV with the crucial 50g/km threshold, this implies a UF of 72%.  The 50g/km is important because it is a widely recognised benchmark for "ultra low emission vehicles", below which manufacturers receive supercredits towards their fleet average CO2 targets and many consumers receive significant tax benefits.  However, according to a recent report from the International Council on Clean Transportation (ICCT)3, the UF may currently be around 37% – this would imply real-world CO2 emissions of around 115g/km, worse than the best full hybrid electric vehicles", says the company.

Julia Poliscanova, senior director for clean vehicles at T and E, said: "Plug-in hybrids are fake electric cars, built for lab tests and tax breaks, not real driving. Our tests show that even in optimal conditions, with a full battery, the cars pollute more than advertised. Unless you drive them softly, carbon emissions can go off the charts. Governments should stop subsidising these cars with billions in taxpayers' money.

"Once the battery is flat, the three plug-in hybrids can only drive 11-23km in engine mode before they overshoot their official CO2 emissions per km. This is contrary to the misleading carmaker narrative that PHEVs on sale today are suited for long journeys. In fact, they have to be charged much more frequently than battery electric cars, which do around 300km on a single charge.

While carmakers blame customers for using the engine too much, the PHEV models on sale today often lack the necessary EV power, range or charging speed. For example, two of the three cars tested, the BMW X5 and Volvo XC60, cannot fast charge. And even the Outlander’s manual states that the engine may start if the PHEV system is too hot or too cold, if quick acceleration is applied, or if the air conditioning is operating.

Ms. Poliscanova says: The truth is that most PHEVs are just not well made. They have weak electric motors, big, polluting engines, and usually can’t fast charge. The only way plug-ins are going to have a future is if we completely overhaul how we reward them in EU car CO2 tests and regulations. Otherwise PHEVs will soon join diesel in the dustbin of history.

She adds that "selling plug-in hybrids makes it easier for carmakers to meet their EU car CO2 standards as PHEVs are currently given additional credits. Top-selling PHEVs all behave in a similar way. This includes cold external temperatures triggering the engine to switch on in the Volvo’s XC90 SUV, the Mercedes-Benz E Class executive car, as well as the Kia Niro. The Mitsubishi Outlander SUV has an "EV" button but the engine switches on with the adaptive cruise control or with high or low external temperatures.

'Jaguar Land Rover’s Range Rover and Range Rover Sport plug-ins will start their internal combustion engines if more power is required than the electric engine can provide alone, as will Porsche’s Cayenne. The Mini Countryman switches on the engine if you drive faster than the electric mode allows as do BMW’s PHEVs.

It is simply not enough to fit an electric motor and a small battery to an internal combustion engined car for regulatory and tax advantages and mark this as a job well done. PHEVs on the market today emit nowhere close to the low CO2 claimed; they are designed as a compliance trick for CO2 rules and to benefit from tax incentives', she concludes.