Ethanol as car fuel is quite common in Sweden. The fuel is called E85 and is 85% ethanol and 15% petrol. It goes in the normal fuel tank and can be mixed with ordinary petrol. The most common car is the Ford Focus, but Saab has just joined in. To modify an old car costs around £1000. Biggest problem is starting from cold. At M5 deg C, E85 will not ignite. You need a block warmer to heat the engine first. OK if you are at home, but not much good in a cold carpark! Also the fuel is less dense than petrol, so you get less miles/tank, but pricewise it is a good bet at present tax levels. In a warmer climate it would be a good idea.