E10 fuel contains less carbon, which reduces the power created at the point of ignition, making the engine less efficient. Vehicles will need to burn more E10 fuel to reach the same amount of power as E5 fuel – in most cases 5% – 10% more. So any gains made on ‘cheaper’ fuel will almost certainly be wiped out by having to use more of it.
Most vehicles Build after a certain date (I think it’s 1994, but wouldn’t swear to it) should be able to run on E10 petrol. If in doubt, check if the inside of the petrol flap on your vehicle states whether it can run on E10, or check at the car manufacturer’s website.
Gov.UK also has a website listing vehicles that could be adversely affected: