Last week I put my car on 70 with cc for a 60 mile trip and it averaged 35.9 mpg on the computer readout (which is prb around 33.8 ish in reality). That was with 2 ppl in the car, and a trunkfull of luggage. Few hills on my trip, but I would have to say that the mileage is still a bit better than what you are reporting. Perhaps ask your wife to try out the cruise control and see if it makes a difference?