I have an F450, auto with a 4.30 diff. I drive 55 Mph most everywhere. I have been getting 10 - 11 MPG depending on conditions (that's without my trailer of course). The past two days I have miraculously all of a sudden gotten 17.5 MPG consistantly. The truck is stock. no tuners or bigger tires etc.. I now have 23000 miles on the truck, and I'm wondering if that is the break in point? Has anyone else got some miles on their trucks and experienced this jump in MPG?