My MPG Calculations were 0.5 mpg Off!

On a good note I saved 20 cents a gallon today at chevron.

But my little screen said I got 20.7mpg and my calculations gave me 21.2.

Not bad for a manual tranny Tacoma with 800 miles on it. I hope to see it improve.

 

Like finding a 20 in your jacket when that first cold front comes through. Nice.

 

I calculate all my fills "manually" and the computer is always lower by .3 to .6 mpg. But I am also adding 2.5% to the miles on the trip meter since the odometer is short by 2.5% based on GPS measurements. I have some suspicion that the odometer inaccuracies may have been addressed with the AT TSB (since the digital and analog speedometer no longer seem different) but haven't been on a long enough continuous drive since the TSB to confirm.

 

Are "actual" tire size taken into consideration from the factory? Could be the 2.5% error.

 

My digital readout is the most accurate of any vehicle that I have driven. It is always within .5 or less every time I fill up.

 

My dad's tundra is always within .1 or .2. Sometimes right on.

 

I agree completely! My Ram was always 1-3mpg off my manual calculations

 

Crap. My Hyundai was off a good 5-8 MPG. Real world 0.5 is damn near perfect.

 

Hmm. That's odd. Like I said my dad's tundra is essentially perfect. I had an 09 cobalt ss that was essentially perfect. Not sure why ask your guys were so off.

 

Mine is always slightly conservative (0.3-0.6 MPG). I like the fact that it always errs on the low side.

 

Your calculations are wrong because your inputs are wrong