Quote:
Originally Posted by n55x3
I definitely take the computer's estimate with a grain of salt but I equally take the manual calculation numbers with that same grain of salt. The manual calculation works if it is always you filling the vehicle up at same temps, exact same gas station and exact same pump, etc. Some pumps shut off sooner, some later.
Honestly, the only way manual calcs can be very accurate if you only ever put in the exact same volume after each fill up. Say you put in exactly 10 gallons every time then that is a repeatable controlled variable that stays constant. I'm too lazy to do that though. I just top it off every time to maximize the time I spent away from said gas station.
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Or, for overall numbers, keep track of miles and fuel used overall. I've driven my 28d for over 8600 miles so far, and have an overall average of just over 30 mpg. The computer generally overstates the mileage vs manual check. Sometimes by just a little, sometimes by a couple mpg.
It is probably skewed a little bit by more highway miles vs city than I would normally drive, counting a trip to Nebraska and one to Illinois from Oklahoma.
But one time calculations can be off. How is the wind that day? If you are fighting it, it will hurt. If it is behind you, it helps. How many hills? Speed?