Avg Fuel MPGs not Reflecting Avg Trip MPGs???

I've recently switched my dash layout to give me the Avg Trip Fuel MPGs over the Avg Fuel MPGs .

Its strange, because my driving routine is pretty steady, working 6 days a week are common place for me and my daily commute round trip is 26 miles round trip usually I'm able to dodge traffic as well (starting my day early and ending late) so I'm not sitting in traffic waiting for red lights usually. Commute consists of 70% interstate, 30% small local roads.

I've noticed since I had my truck (pre-trans fluid check and post trans-fluid top off) the Avg Fuel MPGs has always read high 17's.... no matter what. Baby the Tacoma I get 17.9 mpg's... drive it hard I'd get 17.4 mpgs... didn't make sense.

Now compare that to Avg Trip MPGs display which consistently displays high 19's to low 20s mpg for the same driving. Today on my morning commute I drove pretty aggressive and still squeezed out 20.1 mpg (13.5 mile trip), which for interstate driving (not driving 60 mph in the slow lane) isn't too shabby.

Has anyone else noticed this? Seems like a wide spread between the two fuel economy displays.

Ultimately next fill up I'll calculate MPGs by hand to really tell what's going on.

 

That's how you'll know. And do it over several tanks.

 

avg mpg will not be the same as avg trip mpg.

avg mpg : is based on overall mpg since last reset which can be across multiple tanks or if never reset lifetime avg mpg.

avg trip mpg : will be only for that trip (engine on to off)

avg mpg per tank : this will track the avg mpg per complete fill up of the tank. this is what I use to compare to my vehicle tracking app "aCar"

 

I've reset my Avg Fuel MPGs display a couple of times to try and reflect the Avg Trip MPGs and they still don't come close to each other.