4D55 Performance
Explorer
I think 30mpg is realistic. I get 25mpg on the open road out of my 2005 GMC Duramax 2500 HD Crew Cab with a 6 speed manual. I think my Duramax could do much better than 25mpg if I added an intake, exhaust and a programmer. This new engine only has 40% of the displacement of my Duramax. It's amazing what they can do these days. A few years ago I was like, they will never meet those CAFE standards, but things are looking up.