First of all, thank's to everyone for there help. I think i have found the problem. Put on the GPS today, i set it for a town about 35 miles south on one road, set the trip meter to zero, and counted down ten miles on GPS. Ok the GPS showed 10 miles, the trip meter showed 5.8 miles. About 42 percent difference. Did the same for 20 miles, trip showed 11.5 miles 42 percent again. Ok now how to solve the trip/ odometer problem. Seems like this would be electro mechanical problem in the speedometer? Any where to see how the speedometer works?? By the way, mph is about normal, indicated speed 60, GPS reading 55 mph. Allowing for the 42 percent difference, them my last mileage check would be about 35 mpg. Considering a Texas speed limit of 75, and traffic going about 80, that's about right. So at 60 mph speed, i should be in or arround 40 mpg.