Plug-in hybrids ‘pollute much more than advertised’, says study

Carbon dioxide emissions from the latest plug-in hybrid vehicles are up three times higher than advertised when their batteries have been fully charged, a green transport think tank has warned today. 

Transport & Environment said that while plug-in hybrids, known as PHEVs, are being presented as a climate solution and a stepping-stone to full electrification, tests conducted in partnership with Graz University in Austria show that the newest models ‘pollute significantly more than claimed on commuter routes’. 

Additional pollution measurements taken from three of the latest PHEVs found that they can emit up to seven times their advertised carbon dioxide outputs on a typical journey through city centres when their batteries are flat.

The environmental group has called for the UK Government to stop providing green tax breaks for PHEVs and ban new models from sale at the same time conventional petrol and diesel cars are removed from showrooms in 2030.

Two years ago, T&E found that PHEVs – which combine a small battery and electric motors with a combustion engine, commonly a petrol – polluted significantly more than advertised on longer routes. 

However, its latest review has found that they fail to meet their ‘official’ emissions targets when driven into cities when motorists use them for commuting to work.  

The findings are based on the measurements taken from three recent PHEV models: a BMW 3 Series 330e xDrive (from £46,430 in the UK); Peugeot 308 Hybrid 225 (from £41,140); and Renault Megane E-TECH Plug-in Hybrid 160 (not sold in the UK).

It found that the trio all emitted more CO2 than advertised when tested on the road, even when starting with a full battery. 

The BMW polluted three times its official rating when driven on a typical commuter route, according to the tests by Graz University of Technology. 

The Peugeot 308 and Renault Megane plug-in hybrids performed better but still polluted 20 per cent and 70 per cent more than claimed, respectively, despite the relatively short 34-mile round-trip as part of the test.

The BMW tested as part of the Graz University of Technology report was a 330e xDrive, which in the UK costs from £46,430

The Austrian university used emissions measuring technology on the three cars while driving them on designated commuter and city routes. The image shows the Peugeot with the pollution-measuring equipment attached

Even on a fully-charged battery, the BMW emitted three times the amount of CO2 it is advertised as producing, the report says

The study also measured the electric-only driving ranges of each car.

In city driving, the Peugeot had just over half (53 per cent) of the advertised electric range on a single charge while the BMW had only 74 per cent. 

Only the Renault had the electric range claimed, which is 31 miles on a full charge – which T&E said still might not be enough for many commuters to complete a round trip to work. 

Transport & Environment said PHEVs are wrongly being presented as a climate solution and a stepping-stone to full electrification

When tested with an empty battery, the BMW, Peugeot and Renault emitted between five and seven times their claimed CO2 on the road, as shown in this table

With the UK Government set to outlaw the sale of new petrol and diesel cars from 2030, some plug-in hybrids will be allowed to remain in showrooms until 2035.

Ministers have said only hybrids that can ‘drive a significant distance without emitting carbon’ will stay on sale until the middle of the next decade, though still hasn’t clarified what a ‘significant distance’ is.

After finding that PHEVs are emitting more on the road than advertised, the think tank says only plug-in hybrids with a minimum electric range of 80 miles and the ability to fast charge should continue to be allowed to be sold until 2035.

Richard Hebditch, director at Transport & Environment UK, said: ‘Plug-in hybrids are sold to drivers and governments as part of the climate solution. The truth is they pollute far more than advertised and are a dangerous distraction from full electrification. 

‘In city and commuter tests, they pollute significantly more than advertised. 

‘The Government’s plans to decarbonise driving must be based on the reality of their emissions, not on the industry’s claims.’

Around half of all new PHEVs registered in the UK each year are currently company cars because drivers can benefit from lower taxation. T&E says this shouldn’t be the case

Some 101,414 plug-in hybrid cars were registered in Britain in 2022 – and a further 9,109 last month, according to the latest SMMT figures published this week.

However, company cars make up half (51 per cent) of new PHEV registrations in the UK.

This is predominantly driven by lower benefit-in-kind taxation for employees and lower vehicle excise duty compared to full combustion engines. 

But T&E adds that research shows company car PHEVs drive the vast majority of miles on the engine and are rarely charged by their keepers. 

When tested with an empty battery, the BMW, Peugeot and Renault emitted between five and seven times their claimed CO2 on the road. 

T&E said the Government should tax private car and company car PHEVs based on their pollution in the real world.

Mr Hebditch added: ‘The UK is publicly committed to phasing out of sales of new petrol and diesel cars by 2030, but has left a backdoor for fossil fuels in plug-in hybrids. 

‘The reality is that PHEVs are still big polluters. 

‘Unless there are tight rules about what will be eligible, we risk locking in CO2 from cars right through the 2030s rather than the fully electric future we need.’

Clever tech or a bit of a con? Hybrid BMWs are said to be able to detect when they’re entering a low emission zone – like London’s ULEZ – and turn off their combustion engines. But T&E said this wasn’t always the case when it tested a BMW PHEV in Graz

London – which has the ULEZ – and Birmingham – where there is a Clean Air Zone – are among the cities chosen to pioneer BMW’s zero-emissions technology which is now being fitted to its most popular plug-in hybrid vehicles

T&E tests BMW’s zero-emission geo-fencing tech – and finds it isn’t working

German car giant BMW in 2020 introduced geo-fencing technology that automatically switches its PHEV models to zero-emission electric driving mode only once they enter the boundary of cities. 

However, when tested in Graz, the 3 Series PHEV used for the study ran its petrol engine twice. 

Tests also suggest that the BMW could be saving battery charge when outside cities in case of entry into geo-fenced areas. 

T&E said geo-fencing technology does not guarantee zero-emissions driving in cities and, potentially, risks increasing CO2 emissions outside such zones.