Necro-ing this thread to see if anyone's gotten any higher mileage than this ('19 GT1).
Filled up, got on the highway and drove for 295 miles, 99% of it in cruise control at 75-80 mph, very little traffic on I10 from El Paso to Tucson. Biggest problem was a bit of a wait at the BP checkpoint. Took the picture at the first stoplight soon as I got off the highway.