I never had a diesel before but my prior experience with gas trucks was tainted with getting 13-15 mpg. So I opted for the diesel with the allison. Wow. I get 19mpg average and on highway trips I average 21.5. I put about 31000 on it so far in 10 months of ownership and I have no complaints. The true genius of this whole setup is the transmission. In tow/haul mode it downshifts for you when you brake while matching revs. Really saves the brakes and instills total confidence in pulling heavy loads - skid steers, tractors, trailers full of blocks, etc. I get about 15-16mpg while towing on the highway. Great truck!
Allison transmission is awesome and limitless power from the diesel. Very quiet on the road.
Smaller tailpipe. People think I am trying to make a statement...