Has anyone ran a GPS speedometer while driving? I don't know what Ford's standards are, however my speedometer is about 2 MPH off. (in Ford's favor.) I have a 2013 6.2, supercab, longbed, 2wd, w/ 3.73. At all ranges, the speedometer shows that I am actually going 2 MPH faster than the GPS says. I ran it against the GPS in my Magellan, and in an app on my phone. Both the Magellan and the phone app were spot on (running at the same time.)
Yep, mine reads high also and when I made a comment about that in my "first impressions" post after I took delivery a few folks chimed in with similar experiences. My truck is 4X4 with the 4.30 gears. I figure that eventually I'll put a slightly larger diameter tire on and it'll balance out.