I've done 5k miles in my 40D and have done trips of 100 miles with well over 40mpg returned, imperial gallons though. It all depends on how hard you drive it I find.
I drive it quite hard so generally have a lower mpg around the low 30's but if I want to drive economically I can easily get over 40mpg.
In my previous car, an RX450h, I rarely got over 30mpg but if someone else drove it they would regularly get nearly 40mpg on a decent length trip, all down to driving style in my experience.
The biggest cause I can see is that I usually cruise on the motorway at about 85mph, traffic and conditions allowing, just dropping this to 70/75mph makes quite a difference to the mpg & range as well as not nailing it away from the lights, just because I can
