Tesco only allow me to put £60 in at a time and that gets me about 330 miles, mainly motorways, but playing when I can. The mosts I've seen is over 400miles from my trip to ESR last xmas on the way up from Blasingsmoke to Sunderland.
Trip computer says about 28MPG, which compared to my Leon which gave 33MPG on average on the same commuting, it aint too shabby.