Went on an anniversary trip/vacation to South Padre Island this weekend. I had not paid attention to how long it had been since I last had gotten gas. The light came on and I happened to be very close to a Buc-Ee's (those in TX know what I'm talking about) and stopped there and looked at the miles:
This is on a 2013 2wd Plat w/ 3.31's, 26 gallon tank, MPT Perf-Race Tune. Most highways down this way are 75mph speed limit. As you can see I averaged less than that for the trip but this was more than half the trip there, all the driving around, and then almost the whole way home too. Not bad
Hand calculated mileage came to 21 almost exactly. It used right at 23.888 gallons to fill up so the calculation was a bit off.