Without a doubt the best truck I have ever owned. The more I drive it, the better I like it. Fuel ecomony is 18-24 highway . In town is 16-18. High headwind, tall hills and foot to the floor bring mileage way down. Not lacking power for anything I do. Quiet, smooth and comfortable. Normal conversation at any highway speed is not a problem.
Climate control - set the temp & forget. Duramax w/cruise control constant speed w/no shifting, no matter the hill. The economy at reasonable highway speeds really helps out. 20-24MPG under 70 & flat. I guess the main thing is the smooth, quiet, comfort. It really helps on the 16 hr drives I do.
A fold up console in the front seat for a bit more room instead of buckets. Up governor limit above 95MPH. Improve front seat adjustment with rear seat down. Provide lock for annoying accidental auto seat adjustment & seat heaters. Provide wiring for aux fuel tank or allow computer to accept add'l tank.