With my Hypertech on the Premium setting I average around 16 - 17 in the city and 18 - 20 on the Highway. I have the 3.55 gears, 18" chrome/plastic clad wheels and 265x60x18 Goodyears. I've found that wind really affects this truck. More than any other I've had. A good head wind makes it feel like I'm dragging a boat anchor.

Anyway, I've been playing around with Tow/Haul mode and find that by leaving it in that mode up to 70 mph I actually get better gas mileage. The engine isn't lugging as much. We have a lot of hills around here and in regular mode the engine would just lug up them or kick in and out of overdrive a lot. And when I hit the highway (75 mph speed limit), it seems to get the best mileage around 78 - 80 mph.

I think if we didn't have any hills and did an all highway trip I could probably pull 21 mpg out of it.

One other thing about this truck that I find odd is that it is fatiguing to drive it. I've only had one other vehicle that was like this and it was a 2000 Dodge Grand Caravan with the small V6. It feels like you are fighting it every step of the way whether it be steering or getting it to go, or keeping speed on hills or etc. The power is just to high up in the RPMs or the 3.55's are just the wrong gear set for this truck due to weight and engine.