More leaks
Besides a risk of fuel leaks, rubbers and resins can get partially dissolved, producing deposits that could foul carburettor jets.
Corrosion
Ethanol can become acidic and cause corrosion of aluminium, zinc and galvanised materials, as well as brass, copper and steels coated in lead or tin.
Should I use E10 petrol in my sports car?
Many performance cars – the BMW M5, Mercedes-AMG A45 and Porsche 911, to name a few – are designed to run on high-octane fuels, typically demanding 98 RON or better. Currently, fuels with these octane ratings are still E5 blends.
That isn’t to say that you can’t run them on E10, but you might notice a slight change in the engine’s power delivery: regular users of super-unleaded often report that their car ‘feels’ more responsive, especially in the low to medium rev ranges. Many independent studies have revealed the modest power gains that can be gleaned from higher-octane fuels, with testers reporting subjective improvements on the road.
If you want to make sure you’re getting the most out of your car’s engine in terms of performance and fuel efficiency, then super-unleaded is still the way to go.
Yes, it’s more expensive to buy, but factor in a slight increase in fuel efficiency over 95 RON unleaded – particularly E10 – and the cost difference might not be as noticeable as you expect.
Does E10 fuel give lower MPG figures?
The US’s Environmental Protection Agency has estimated that E10 can reduce fuel economy by 3-4% compared with fuel that does not contain any ethanol.
This happens because ethanol contains around 33% less energy than pure petrol. So you have to burn more of it to achieve the same power output.
Nonetheless, if your car’s user manual says it’s compatible with E10 fuel, then there’s no reason why you shouldn’t use it. Apart from that drop in fuel economy compared with the E5 alternative, there should be only a minimal difference at all in the way your car drives. If you’re unsure which fuel to use, always consult the car’s manual.