I tried this also. My car does get 2-3 mpg better milage on a long highway trip (according to the onboard fuel economy computer) if I leave it in 7th gear manually rather than D. I have no idea why that is as I am relatively certain that its in 7th gear anyway. I am totally confusued. Maybe its some electronic gremlin..... ?

I did not do anythign crazy, I just put the car in DS shifted to 7 and just left it there. Upshifting around town seems totally useless to me. if people drive in manual mode 90% of the time why not get the 6mt car?