In 2006, I bought a 1995 Nissan Micra for £800 (manual, not automatic). It was fairly well-used, with 80,000 miles on the clock, but I still got 40-45 miles to the (UK) gallon with it. In terms of petrol/gas amounts, it had a 9-gallon tank and I spent about £20 per week on fuel (about half to two-thirds of a tank), driving 200 miles per week.