Liquid Petroleum Gas, sometimes called Autogas on garage forecourts. It's brilliant! You'll need a car that has been converted to LPG (there are a few that are factory fitted) and that's IT. Fuel is about 70p per litre and the consumption is about the same as petrol, so you are instantly getting double the miles per gallon. It's very clean and has fewer emissions. You might have to look around for garages that stock it, but many BP and Shell garages do. We are on our fourth LPG car and we're never going back.