Another fuel mileage thread/overhead readout thread

[DPKetchum]

I've NEVER hand calculated fuel mileage before and keep reading about the acuracy(or lack of)of the overhead readout. Well I hand checked mine today. By hand 17. 69 mpg. Overhead was 17. 9,thats mixed two lane,stop and go and some interstate at 70mph. Truck just turned 18k on odometer.

 

[Pawpaw]

The last time I checked mine, all highway from Las Cruses NM to Dallas, I hand calced 20. 3 MPG. The overhead showed 18. 8.



My overhead consistently reads 1 - 2 MPG low.



The only way to get an accurate measurement is to fill it up until you can see fuel (not just foam) inside the filler neck. You have to do this on both fill-ups to have any accuracy.



Bob

 

[TSpecht]

The overhead on mine always seems to be within about 1mpg of hand calculated. It tends to err on the optimistic side, but I have seen a couple times where it was low compared to hand calculated. It seems to be lower than normal when I drive fast down the interstate (~80mph) for about half a tank, and then go to regular highways (~55-65mph) for the rest. It seems to be just like grade point averages, it's easier to make it go down than it is to bring it back up... haha

 

[bpenrod]

Mine was within 1/2 mpg when stock. Now with the fueling boxes on it typically reads three mpg high. Same accuracy, just 3 mpg high on the readout! Truck gets between 20 and 21 highway with a little two lane thrown in (10%). Just put a GV overdrive in so my cruising rpm at 75mph is down from 2300 to 1750. I'm hoping that may squeek out another mpg or two for me.

 

[sarj]

I just made my first long run, 850 each way, across the desert, and through the mountains, Interesting part was that I just had the TSB for the reflash done the day before I left.



Before the reflash, I'd see 18. 2 tops running empty on flat highway. The overhead was 16. 3, but I'm on 315's and I haven't corrected the speedo. Corrected for the tires, the overhead would have been 17. 6.



On the trip, the best I saw was 21. 8 @65 mph by hand, mixed hills & flat @ about 70-75 was 18. 8, and hard up and down was 17. 8. The overhead was closer after the reflash on all cases, and was actually higher doing 80 across the desert. The overhead was 18. 9 with no correction for the tires while actual was 18. 8. Just turned 8k on the truck.