hand calculated, my wife says I drive like a grandpa, I've found that if I dont go above 68mph i make good milage. I actually posted on the diesel stop with a photo of 21.2 mpg, had corrected its almost the same. thats sustained highway driving for a considerable distance, earlier this summer i went from cleveland to indiana cruise set at 75mph and made 17.8 the entire way.
gunman, it seems these trucks are not equal at all, meaning some get decent milage, some get horrible milage, some have had many serious problems, others not. I guess its a roll of the dice, and it shouldn't be either. Anyways, I love the truck, I looked around too, looked at GM, (had a previous Duramax that was good) looked at Dodge at local auto shows and just didn't like the truck, same with the new GM's, they just dont seem to compare when looking at suspensions etc. GM wouldn't give me answer if I could put a plow on their truck. Ford said bring it on. By far I think my Dmax had the best milage over 20 mixed hiway/street driving. But oh-well, I like this truck much better.