I concur with Hightower. My first motorway return trip down to Kent from Derby I managed 362miles on full tank (light came on), refuelled 29 litres on return. I was pleased @ 56.7mpg approx but can see there is room for improvement. To be fair I was doing 70-80mph most of the way with a towny drive whilst down there, approx 30 miles.
Matt
Matt