Just recently drove back from Dusseldorf in Germany where I was visiting my eldest boy and filled up again in Dover. The LS made it back on one tankful of gas and averaged 24.5 mpg. This was mostly at 80 mph (or slightly more occasionally), on the motorways through Germany, Holland, Belgium and France. I thought this was good going from a 4 litre V8 on lpg and, of course, it was a very relaxing drive. No tiredness or bum ache. Marvellous.