Depends how you look at it
Given that Petrol & Diesel prices are made up mainly of taxes and duties a low consumption car protects you a little bit from the confiscatory high tax regime in the UK
It may surprise you to learn that UK tax and duties on petrol and diesel are 18% higher than the next EU country and 80% higher than the unweighted average
Tax is currently at 59% and was as high as 85%
under Gordon Brown, himself a non-driver
So its not the consumption of the car that worries me, its the fact that about the only thing I can do these days without paying tax is fart.