Mpg reading different from dash

Trying to figure this out so stereo is showing different number than the dash on mpg ?

 

My best guess - the head unit is showing the current tank MPGs and the dash display is showing you the most recent trip MPGs.
They would not be the same.
What matters is the overall tank MPGs (fill-up to fill-up) cuz that's what you're paying for.

 

yep, the specifications behind what's being averaged matters.

"9 of 10 people die!"
"1 in 65 newborns go to college"

 

Range is a long-term estimate based on a "lifetime" of driving. Your last picture is the summary of the trip you just completed.

In my experience the only number that matters is ""current MPG" which jumps much but tells me which "skinny pedal" usage tend to use gasoline stupidly.

 

If you have just filled up I find the mileage is lower but after 10-20 miles it gets closer expected mileage.

 

I see the word "Average" in the second image, vs. "Latest" in the first.
Real MPG figures come from your calculator! Divide the miles traveled from last fill up by the gallons to fill the tank.

 

It resets everytime you gas up on the instrument cluster.

 

Not quite everything. If you are pulling a teardrop camper for your 2-week annual vacation, the "range" estimate is high at first, gets more accurate during the 2 weeks, then is low estimate for a few weeks after you return.

But true ... "latest trip" and "right now" change much.

 

One says "average", the other says "latest". Both are approximations because the fuel system lacks a flow meter.

 

When the truck rolls to a stop from lack of Taco-sauce and you have driven "X" miles ... that number is accurate.

 

This^^^^^
The mpg shown on your instrument panel is notoriously inaccurate. I ignore it. Fill tank, drive, fill tank again. Divide gallons used into miles driven since last fill. Yep, old fashioned way, it works, it’s accurate.