I am still paranoid that I am going to wear the tires in the center at 37 PSI. At about 3300 miles or so now though, I do not see any bad wear patterns. I have not seen too much data regarding if such high PSI settings will prematurely wear the tires out.

 

My display MPG is all over the place. Sometimes right on, sometimes up to +/- 3 mpg. I think of it as a rough indicator, like the gas gague.

I would definitely record mileage and gallons separately. Any issues with pump shutoff inconsistencies and such will average out over time. On a single tank they can have an effect, but over time, if you report all your tanks, the database will calculate your total mileage vs total gallons, so at most the figure will only be off by the inconsistency of a single fillup (your last one). So the more you drive the more accurate your results will get.

If you report the display mpg or some combination, your error could multiply over time, or at the very least miss out on the long term error reduction you get from reporting miles&gallons.

After you've put a few thousand miles on the car, the little difference in pump shutoff will have a negligable impact on your figures. You know exactly how miles you've driven total, and how many gallons you've put in the car in all your fill ups. The last time you filled up may have had some error from pump fill level, but over the hundreds of gallons you'll put in the car over time, even a whole gallon of error will have a small fraction of a percent impact. So over time the miles&gallons reporting is guaranteed be much more accurate.

 

I run mine at 40, they had 14k on them when I got the car, I have put 18k on them since then, and they're wearing quite evenly. No issues.

 

I don't think that it's possible to get uneven wear from overinflation with a modern radial. Thel all have steel belts built into them which hold the shape quite nicely. You wouldn't want to do with with old bias-ply tires but that's a different animal entirely. If anything, wear will be reduced since extra pressure reduces sidewall deflection while rolling.

The only potential problem I see with over inflated tires is faster wear to suspension components, which won't have as much of a cushion between them and the bumps. It might matter, it might not.