and the odometer reports too low (which is why my FE calculations are 2% less than what the OBD is telling me).

You and the OBD are using the same "wrong" odometer reading. It's not that much, maybe 0.3 mpg for the folks near the 39 mpg mark. On average over 12,500 miles I've found about 0.9 mpg error in the readings between the OBD and calculated actuals. The odometer reading won't affect that. The only thing you can do with the odo reading is simply use it as a correction factor after all calculations are made. Since it's only 1.5% I wouldn't worry about it.




However some have found their speedo to be off by 5% and if the odometer was 5% then that's a lot. However the errors in the speedo and odometer don't appear to be consistantly the same.


I also noticed difficulty comparing my speedo to the GPS. I would feel the car slightly slow or accelerate while the GPS rerading bounces around but the speedo would not move significantly. It appears to have a soft "dampened" or delayed operation. I assume since everything is electronic they don't want the needed vibrating like my 70's cars did.