SuperC,
I almost didn't believe my first 40+mpg reading, but in warmer weather, highway speeds around 60, no major climbs, I've found that 40+ is very doable. I just don't have regular routes under those conditions to get a tank at that mpg. Still, I'm very happy with around 34-36 pretty regularly overall. Some miles on the car do seem to improve mpg, but your own driving practices are probably more responsible for the great early mileage.
Lewis