Attention: TDR Forum Junkies I've got just under 16K on my '03 2500 QC 4x2 and I record every fillup. I reset mine at every fillup and it's fairly accurate although it usually reads 1mpg low. I've found that as long as you drive under the same conditions (all city or all hwy) it's pretty accurate. If you mix up stop and go with some hwy and some heavy loads it might not be as accurate.
BTW, The worst I have got so far is the very first tank, 17. 1mpg. I usually get 19-20mpg city and up to 23. 7hwy (no a/c) at 65mph. I drove from Seattle to Ohio last summer, set the cruise at 80mph and got 19-20mpg (with a/c on too) through the mountains and 20-21mpg (a/c on as well) on the flats. I haven't pulled anything heavy yet since I still don't have a trailer for my racecar.
BTW, The worst I have got so far is the very first tank, 17. 1mpg. I usually get 19-20mpg city and up to 23. 7hwy (no a/c) at 65mph. I drove from Seattle to Ohio last summer, set the cruise at 80mph and got 19-20mpg (with a/c on too) through the mountains and 20-21mpg (a/c on as well) on the flats. I haven't pulled anything heavy yet since I still don't have a trailer for my racecar.
