By Natalie Marchant
Moves to introduce a new greener blend of petrol may cost UK drivers billions of pounds a year, experts have warned.
E10 fuel contains 10 per cent bio-ethanol and is being rolled out across the country to meet the EU's Renewable Energy Direction, which requires 10 per cent of road transport energy to be from renewable sources by 2020.
But car buying magazine What Car? has branded the move to introduce E10 fuel as "irresponsible", after it carried out the first ever real-world tests on the new blend.
Fuel is less efficient
What Car?'s True MPG testers found the E10 fuel blend is less efficient than the current E5 blend, which is up to 5 per cent bio-ethanol, across every engine type tested.
This means that vehicles would have to use more fuel, thereby costing motorists more.
What Car? editor-in-chief Chas Hallett urged the government to carry out comprehensive, UK-focused testing on the impact of the new petrol.
He said: "The US Environmental Protection Agency (EPA) estimates that the detrimental effect of E10 on fuel economy is between three and four per cent, but even our small sample of tests proves otherwise.
"To lead consumers into E10 without fully communicating the significant impact on fuel economy, particularly for drivers least able to absorb the extra costs, is irresponsible."
Drop in performance
What Car? put E10 through its paces against "pure" E0 petrol to compare its results with the American EPA's tests.
The vehicles used were a three-cylinder turbo Dacia Sandero, a naturally aspirated Hyundai i30, a hybrid Toyota Prius and a four-cylinder Mini Paceman.
The Sandero performed the worst economically, showing a 11.5 per cent drop in mileage on E10.
The 99bhp Hyundai i30 showed a similar drop in performance, with a 9.8 per cent drop.
Each vehicle test by What Car? also showed an increase in carbon tailpipe emissions.
But the Low Carbon Vehicle Partnership asserts that these rises would be partially offset by the renewable properties of bio-ethanol and due to the fact that the crops used to produce it absorbs carbon dioxide while growing.
Smaller vehicle worse affected
The tests also showed that more powerful cars cope better with a higher ethanol content, meaning that smaller vehicles - often bought by motorists on a smaller budget - are worst affected.
Also, not every vehicle will be able to use the new E10 blend.
The Society of Motor Manufacturers and Traders (SMMT) says that although around 92 per cent of cars are compatible, this leaves almost 1.5 million petrol vehicles potentially at risk.
These are also more likely to be older cars, often bought by people on tighter budgets.
The full report and figures of the E10 tests have been published in What Car? magazine.