well it happened again me and my hypermiing! so I know the mpg numbers can vary depending on driving habits. pictures speak for itself. ran out of gas when it still says 22.3. actual fill up ended to be 25.9 gallons.

 

it's a good thing it died close to the exit ramp and i just cruise it to the nearest shell station!

 

Depending on the pump I have crammed in over 26 gallons. I keep track of the DIC fuel used and what I put in. I have the luxury of having the same pump available for most fill ups. That reduces error. 3.5 gallons out of the DIC 22.3 seems off more than 5%. Using my "super-fill" technique of very slowly throttling the pump flow until absolutely NO more fuel will go in, I can put in ( up to ) 2.5 gallons more after the normal click off. But it takes a very long time. So normal fill methods near top off can have easily over a gallon of variation.

I got lucky on I-80 one winter near Lincoln Ne. I had done the super-fill at the cheapest station in the east Denver suburbs. I was trying to make it to Iowa where fuel went down 35 cents. At the exit the fuel used was 24.5 gallons. That was what I had put in back in Colorado.

The exit was down hill to the stop light. In electric I tried to make it down the ramp and as far as I could. On a right turn the engine stumbled since what was left of my fuel sloshed away from the pump. I let off the gas back to auto-Stop. The last 1/8 mile was electric to the pump. That truck was very accurate on fuel used. I probably had a little more than a gallon in there.

Others have been up to 5% under predicted. So when I fill at a trusted pump I watch that DIC and leave a gallon for that 5%. With the wife on-board 15%.

 

it did the same remember when I was in las vegas traveling to Arizona? I believe it also said 22+ gallons used. whenever I fill up, it stops at 22 mpg max. occasionally I get 24 gallons on some scrupulous stations.

 

Yes, station-to-station, pump-to-pump, temperature, all play a factor. Then there is the matter of absolute accuracy of that DIC calculated fuel used value.

 

I guess next time I will fill it up to the brim. my last fill up was a few clicks until I thought it was enough.