Bolt I still say there's some weird magic going on with yours. Even when I do baby the throttle (which is admittedly rare) I can't get anywhere close to 20. Heck I get 16 or so highway, do you drive 55 everywhere? :D

My old 96 dakota with the 3.9 used to get about 22 per gallon on the highway. But to get 21 with a v8, now that's impressive

left foot?

I was thinking the same thing, but in this age of inclusion, who am I do judge?!?! |>))

Looking at these numbers, I'd be wondering if it is a speed/distance sensor thing.

I don't know if it has been adjusted or if it happens automatically, but different gear ratios mean that the computer "thinks" you are going a different speed/distance than you actually are.

Haven't done the math yet (and probably won't), but this may be why you think you are getting better mileage than you are.

"left foot" was an oops, give me a break, I'm old.

In reference to the speed sensor, the reluctor ring (gear) for the speedo and ABS, in a 9.25 rear end, is in the diff, behind the ring gear. It spins at axle speed so it is not influenced by the gear ratio. Nothing has to be done to keep the speedo, odometer and trip computer accurate. There must be something else that effects mileage.
I really think that city mileage improves because less gas pedal is needed to accelerate. Highway mileage drops at cruise because the engine is spinning faster and the extra power is wasted.

Old? Born before Kennedy died or after? (I only ask because it is my first memory - toddling into the kitchen to my mother crying after hearing the news)

I can go home now! I've learned something new, and I think I made both a client and my supervisor happy already today!

"Old" like When President Kennedy was assasinated, I had already joined the Army.
Not "old" like - still crawl around on and under my truck and the '53 Chevy that I just sold, not 'old' like excited about the Cobra that I am getting to replace the '53 Chevy, like still get my wife annoyed because of my vehicular toys. "Old" like 5 children, 11 Grandchildren, one Great Grandson.
Funny thing about "old" - it looks way different from the inside than from the outside.

Ok, so you can use "Old" any way you like to! |>) I think I'm old because my beard was born before most of the engineers that I work with!

But you've got things that keep you active and engaged! You'll never really get old as long as you have that. One day, you will just stop, hope your great grandson has you around long enough to learn about the things you like to do!

it could be the fuel he is using, maybe he isnt running anything with ethanol blended in...IIRC up to 10% ethanol is common place for "regular" and people who locate stations that dont use the ethanol blend get higher mileage