most of my driving is suburban.there is some open places but mostly some stop and go.,,, the trans in 5'th gear on a level road at 45mpg seems ok ,,i do not feel any lag or groaning from the engine. i tried 6'th gear at a minimum of 50 mpg and i think the car likes it. Again this is on level roads. if i am going up even a slight incline ,i agree it feels better to downshift into 5'gear or even 4 under steeper conditions,,my goal is to get the most mpg i can. i have my tires over inflated by 4 pounds so that may help.
thanks for the info....Dennis