My neighbor has a full size GMC pickup truck, with the extra door for passengers. He said it is the type that has a chip, and he got a special chip where he can change the horsepower the truck puts out. I think he said he can put in 70 HP, 90, 110, or 135 HP.

He has it set at 110 HP, and he has a special muffler for the truck too, that might help some.

Mind you, I talked to someone with a similar size gasoline truck just yesterday, who gets 7 mpg when towing a backhoe, and 10 when not towing, and maybe 12 on a good day on the hwy.

My neighbor's diesel truck gets....

are you ready for this........

24 mpg on the highway!!

That's amazing!!

He said when it was stock, he got about 17 mpg.

Could you imagine what my 1991 300d would give, if there were a way to tweak it? (though there's probably not much HP to play with on a car). If he can get that on a full size truck, and my stock MB gives 36 hwy, I'd probably get 55 mpg.