New E10 fuel could reduce a car's economy by 10 per cent

The introduction of new E10 fuel could increase motorists' fuel consumption by more than 10 per cent. The new fuel, which contains 10 per cent bioethanol, will be rolled out across the UK as part of the government’s commitment to reducing emissions.

But real-world testing by What Car? magazine found that vehicles running on E10 are less efficient than the current E5 (up to five per cent bioethanol) blend of fuel across every engine type tested. This means cars have to use more of the new fuel, costing drivers much more each year.

What Car? tested E10 against pure unleaded using a Dacia Sandero, Hyundai i30, Toyota Prius+ and a Mini Paceman. The Sandero registered a 11.5 per cent drop in economy, while the i30’s consumption increased by 9.8 per cent.

CO2 emissions also increased, although the Low Carbon Vehicle Partnership told What Car? that increases would be partially offset by the renewable properties of bioethanol.

The Society of Motor Manufacturers and Traders said that only 92 per cent of UK cars will run on E10, leaving 1.5 million petrol-powered vehicles at risk of not being able to use the fuel.

According to What Car?, the fuel had previously only been tested in laboratory conditions and the potential impact on fuel economy and CO2 emissions had not been communicated to motorists.

The fuel is expected to be introduced to the UK market later this year as part of the government’s commitment to reducing greenhouse gas emissions and conforming to the EU’s Renewable Energy Directive. This requires 10 per cent of road transport energy to be from renewable sources by 2020.

What Car? editor-in-chief, Chas Hallett, called on the government to carry out in-depth tests to understand the financial impact on drivers. He said: “The US Environmental Protection Agency 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.”

For an explanation of how What Car? carries out True MPG testing, click here.