....after 100mi it shows an average of 10.6 mpg.
Is this normal? I'm planning on getting it into maintenance but don't know what to check for. I live in a chill flat place. 60 - 78F
Any recommendations?
That does seem abnormally low.
There's a bunch of stuff you need to check. Mine takes 7 miles and the engine coolant to get to normal and 20 miles for the tranny to get to normal temp. That means you need to drive over 20 miles a trip to get normal fuel mileage. three miles to the grocery and post office and back would be in the 20 mpg range for me.
Look for the threads on intake valve cleaning.
Inspect and maybe replace the air filter.
Buy some spray cleaner and *carefully* clean the MAF sensor.
Run a couple of bottles of Redline SI-1/Fuel System Cleaner through it. That stuff actually cleans injectors.
Check all 4 calipers for dragging/unusual pad wear. Mine were nearly worn out ar 60k miles, esp the rears. The car has a hill keeping assist that makes the rear brakes drag for a few feet. Be sure that is releasing. Check that the sliding pins are lubed enough.
Check your tire pressure. START with the placard pressure as the min.
Have the wheel alignment checked to be sure they are all aimed correctly.
Take it on a trip and do and "Italian Tune-up". Treated properly, my '16 AWD with 90k miles will still get 33+ on the interstate, but 29 is a lot easier.
Find ethanol free fuel for a proper mileage test.