My duramax gets 32-35 mpg higway which is great, only problem is it cost me 135 dollars to fill up 2 weeks ago. Drove to pa and back for an atv trip, 219 miles and less then 1/4 tank! Great on Fuel! Mabe its cost effective to drive it, I dont like to drive it, its my plow/tow truck. I only plow with it and tow my trailers. Now im not plowing with it anymore I guess I should just drive it. I only have 23,000 miles on her so far, since new.