Hello, I seem to have a very very thirsty car, put £10 in and im lucky if i see 20 miles out of it, have checked for leaks, seems to be the odd bit of vapour coming from the driver side but cant see any leaks, anyone had a similar problem? Also the car seems down on power, doesnt rev as clean as it should, how can i get it running nice again? Its on 121k just had a service too..