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Cars running on e-fuels emit as much poisonous nitrogen oxides (NOx) as vehicles using conventional fossil fuels in a new revelation that could be a dagger to the eco credentials of synthetic petrol.

E-fuels have been touted as a potential solution to keep internal combustion engine cars on sale beyond the Government's 2030 ban with claims they can cut carbon emissions by as much as 85 per cent.

However, tests conducted on behalf of think tank Transport & Environment found that motors running on this 'greener' type of petrol emit equally high levels of toxic NOx fumes as standard E10 unleaded sold at filling stations today - and much more carbon monoxide and ammonia - despite having a lower CO2 impact.

It concludes that e-fuels 'will do little to alleviate the air quality problems in our cities' that have been linked to thousands of premature deaths each year.

E-fuels as harmful as petrol: New tests carried out by a green transport think tank claims cars running on synthetic fuel emit as much poisonous nitrogen oxides as standard unleaded

Porsche is one of the headline-grabbing car firms known to be pumping huge funding into the development of e-fuels.

The German manufacturer has invested around $24million into a project in a bid to keep models like its iconic 911 on sale after petrol and diesel cars are banned from showrooms across Europe around the end of the decade. 

Bosch is also known to be investigating the possibility of creating synthetic fuels while Mazda earlier this year became the first automotive manufacturer to join the 'eFuel Alliance'.

However, assessments carried out by French research organisation IFP Energies Nouvelles and Transport & Environment has found they have little benefits in terms of emissions that could be harmful for our health.  

Measurements taken in a lab from a Mercedes-Benz A-Class running on three different e-fuel mixes.

With no e-fuels currently on sale, the French lab produced 100 litres of e-petrol itself with different blends. 

This Mercedes A-Class was used for the tests, taking emissions measurements following cycles using three e-fuel mixes and conventional E10 petrol sold today

The same test cycles were repeated using the Mercedes running on conventional E10 petrol and found that NOx levels were almost identical. 

And while particle emissions are considerably reduced, more than two billion particles are still emitted for every kilometre driven in an e-petrol powered vehicle. 

When burned, synthetic petrol causes almost three times more carbon monoxide – which deprives the heart and brain of oxygen – compared to petrol. 

The e-petrol powered car also emitted up to two times more ammonia, which can combine with other compounds in the air to form particles (PM2.5) for which there is no safe level of pollution. 

The health risks of PM2.5 include asthma, heart disease and cancer.

Julia Poliscanova, senior director for vehicles and e-mobility at T&E, said e-fuels have 'lost the race to clean up cars'.

'No amount of spin can overcome the science of burning hydrocarbons,' she adds.

'As long as fuel is combusted in engines, toxic air will persist in our cities. Lawmakers who leave loopholes for e-fuels in emissions targets are condemning the public to decades more of avoidable air pollution.'

Mazda confirmed this year it had joined the eFuel Alliance - a group of organisations that want to establish CO2-neutral e-fuels as a credible contributor to reducing transport emissions

As well as offering little in terms of eco benefits, the report concluded that e-fuels will very much be limited only for the wealthy.

The green transport think tank claims industry proposals to allow loopholes for e-fuels in EU car CO2 targets will drive up costs for drivers. 

Running a car on e-fuels over five years will cost a driver approximately £8,500 more than running a battery electric car, the report estimates. 

High e-fuel costs will also make running second-hand cars on e-petrol around £8,500 more expensive over the same timeframe. 

'This makes them ill-suited to decarbonise the existing fleet, something the oil and car parts industry advocate for,' says the report.  

It adds that the cost of production is also far higher than electrifying vehicles.

Supplying just 10 per cent of new cars with e-fuels instead of electrifying them will require 23 per cent more renewable electricity generation in Europe, the report states. 

Yet Transport & Environment didn't rubbish the concept of e-fuels entirely, saying they should be prioritised for planes, most of which cannot use batteries to decarbonise and which today burn fossil fuels that may be even worse for air pollution.

Poliscanova added: 'Battery electric cars offer drivers the cleanest, most efficient and affordable way to decarbonise, while synthetic fuels are best suited to planes where electrification is not an option. 

'The credibility of Europe's clean car policy is on the line and any diversion into e-fuels is a new lease of life for old polluting engines.'

European MPs and governments are currently deciding on an EU Commission proposal that all new cars sold in 2035 be 100 per cent zero-emissions – leaving no 'back door' for e-fuel cars.

Porsche pushing ahead with e-fuel plans 

Porsche's greener fuel to be trialed in 2022: The German sports car maker will be testing synthetic petrol in race cars next year

The fuel would not require any modifications to a car and be compatible with both current and older vehicles - and could make existing motors as clean as electric cars when you take into account the carbon footprint created during production and supply

Porsche currently plans to begin trials of e-fuels next year, having been developing its own synthetic fuel it claims could cut CO2 emissions produced by internal combustion engines by as much as 85 per cent.

Initially, trails will be carried out in motorsport applications, with its first outing set to be in a Porsche Supercup race car next year. 

The fuel would not require any modifications to the car or its engine and be compatible with both current and older vehicles - and it could make existing motors 'as clean as electric cars', when you take into account the carbon footprint created during production and supply.

The sportscar maker has been working in partnership with Siemens Energy and other international companies since last year to develop and implement a pilot project in Chile designed to yield the 'world's first integrated, commercial, industrial-scale plant for making synthetic climate-neutral fuels'.

In December, the company announced a new partnership with energy firms Siemens Energy, AME and Enel and the Chilean petroleum company ENAP.

Construction of Porsche and Siemens Energy's new e-fuel plant in Chile is underway, the German car maker confirmed in September

In September, it confirmed that construction had started to build a plant specifically for the commercial production of synthetic fuels in Chile, which will use the location's blustery environment to produce e-fuels with the aid of wind power.

Porsche says it could be producing 55 million litres of greener synthetic fuel by 2024, and as much as ten times that amount two years later.

Commenting on the plans last year, Porsche boss Oliver Blume reaffirmed that 'electromobility' remains the top priority at Porsche but eFuels for cars are a 'worthwhile complement to that' – as long as they're produced in parts of the world where a 'surplus of sustainable energy is available'.

'They are an additional element on the road to decarbonisation,' Blume said in December. 

'Their advantages lie in their ease of application: eFuels can be used in combustion engines and plug-in hybrids, and can make use of the existing network of filling stations.

'By using them, we can make a further contribution toward protecting the climate. As a maker of high-performance, efficient engines, we have broad technical expertise. 

'We know exactly what fuel characteristics our engines need in order to operate with minimal impact on the climate. 

'Our involvement in the world's first commercial, integrated eFuels plant supports the development of the alternative fuels of the future.'

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