The car reported higher fuel economy than I was seeing based on actual miles divided by actual fuel used.
Here’s the fix:
IDD00499-Display correction of consumption and operating range
Make the new value LARGER if the display is too high.
Stock is 100%
e.g. if the car reports 55mpg, but the pump reports 50mpg, change from 100% to 110% (numbers might not be perfect)
Close and quit VCDS before turning off power to the car.
So far I’m at 108%, which causes the MFD to report slightly lower fuel economy than I’m measuring at the pump. I’d rather be slightly surprised than slightly disappointed!
Here’s where I got the how-to: idpartsblog.com