Do you have a 4:10 rear axle ratioIJ If so, that isn't helping your mileage any! Nevertheless, you're still getting nowhere near what one would expect with a diesel, regardless of the ratio. I've spoken to a few credible owners of these trucks who seem to be "echoing" the same story. My dealer has the nerve to suggest that I deal mine in on another one. He says there's been some modifications made to the Bluetec side of these engines. I don't believe him!