The UK is introducing a new kind of petrol called E10 from September, which will replace the current E5 as the standard fuel in the country. E10 is already widely used around the world, including in Europe, the US and Australia.
It contains up to 10% renewable ethanol (from which it gets its name) and 90% regular unleaded.
By blending petrol with 10% renewable ethanol, less fossil fuel is needed, helping to reduce carbon emissions and meet the UK's climate-change targets, the government has said. The introduction of E10 petrol could cut transport CO2 emissions by 750,000 tonnes a year – the equivalent of taking 350,000 cars off the road.
However, these emissions have little impact on emissions associated with air quality and public health. And using E10 petrol can reduce the number of miles drivers are able to drive on a gallon of fuel.
"You may see a reduction of around 1%, but it is unlikely to be noticeable in everyday driving," the government said.
E5 will still be sold at most petrol stations but it will be classified as "super" grade fuel, rather than the current "premium" grade, which means it will cost more.
"E10, on the face of it, is a laudable environmental beneficial approach but millions of motorbikes and petrol vehicles over 10 years old simply can’t take the risk," Howard Cox, founder of FairFuelUK, told Yahoo Finance UK.
"Every garage must supply both E5 and E10 to ensure that both choices are always available. The most important thing though, is that the fuel supply chain does not opportunistically hike prices."
Around 95% of petrol-powered vehicles in the UK are compatible with E10 petrol, including all cars built since 2011. But around 1m vehicles in the UK are not and the RAC has said that drivers of cars registered prior to 2002 should not to use E10, as problems have been reported.
Some examples of incompatible vehicles include classic cars and some mopeds, particularly those with an engine size of 50cc or under.
One report has said almost all Ford cars sold in Europe since 1992 can run on E10, as can most Renaults sold since January 1 1997. Likewise, all Harley-Davidsons sold since 1980 should have no problems.
If drivers are forced to put E10 petrol in a non-compatible vehicle, or do so by mistake, they should simply fill up with E5 next time. They don't need to drain the tank.
"On a one-time basis, your vehicle will not suffer engine damage as a result. Prolonged use of E10 petrol in a non-compatible vehicle, however, may cause harm and is not recommended," the government said.
The RAC has said that if drivers put E10 fuel in an incompatible car it will still run, but seals, plastics and metals may be damaged over longer periods as a result of bioethanol's corrosive properties.
It is also safe to mix E5 and E10 if a vehicle is compatible with the latter.
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