Originally Posted by andrewwynn

I like and use the swing mpg gauge. I will watch it while climbing hills and bump cruise control down 1mph when the sweep drops to 20 and repeat unitil I crest the hill or hit 5-6 mph drop. On the way down the hill I'll speed up 1mph every time it gets higher than 30.

Using that method I've been able to bump mpg on a 300 mile trip from about 21 to 23 (11% better).