OK, so I drove 265 miles , 75% city and 25% freeway, always way over 100 degrees and AC on full blast. I just drove normal, not trying to get the best mileage (real world). I filled up at the same station, but the pump I used last time was out of order.
Ultra-Gauge reported 265 miles driven, AVG fuel mileage 14.8, Fuel left in tank 12.6 gallons.
Actual values, It took 18.1 gallons ( 11.9 left in tank, accurate enough considering not the same pump) , calculated 14.64 MPG.
I had 12 gallons left and the stupid gas gauge needle was saying 1/8th tank (ever since FP replacement.....twice)
Oh yeah, this morning on the way to work 10% city 90% freeway 18.1 mpg doing 75 mph.