Alcohol-based fuel, generally made from crops such as sugar or corn, but potentially also from waste matter such as plant stalks and even landfill.

Because it lacks lubricating oil needed in an engine, ethanol is usually used as an additive in petrol – E10 contains 10 per cent ethanol and E85 contains 85 per cent, for example.

E10 is quite common now and can be used in most cars, but a number of car-makers (notably GM Holden) are moving to E85 compatibility for environmental reasons.