I have had this problem....consistently. I have the info set to reset with refuel automatically, and as a matter of habbit from previous cars, I reset the trip meter every time. After about 400 miles I find that there is maybe a 10-20mile discrepancy between the trip meter and the nav information. (NAV is always lower than the trip). I don't see it as the biggest of deals. As you know by now, the NAV doesn't always have a 100% read on you. In other words, often times when I am starting out on a trip, I will be "off road" for maybe 50-100 feet. So just chalk up the discrepancy to things like tunnels and such where it loses contact.