Of all the vehicles I've ever had, interestingly enough, the EVIC on this truck for me has been the most accurate. I don't bother with splitting hairs about what part of a tank I was getting what mileage at. I calculate from full to the next time I fill up, regardless of what type of driving in between. With that, I'd say that most of the time, the discrepancy between the hand calculation from Fuelly to the EVIC has been within a couple tenths. From time to time it has been 1-2mpg off, but those times are the exception to the regular readings.In the spirit of telling the TRUTH... My above calculations on this were all based off of the EVIC calculated mileage..... which as I have said many times and will continue to, IS NOT ACCURATE! I filled up and the EVIC said 26.2 mpg. Hand calculated said 22.8 over the whole tank with 460 miles on it.