With the recent warmer weather in Chicagoland I managed my best tank ever!
I filled the tank with 15.082 gallons. 46.5 MPG. My calculated MPG has always averaged 1.2 MPG less than the display.
I think the biggest help was the tire pressures increasing to 45 PSI. They were inflated to 40 in the cold weather. About 2/3 way through the tank I bumped them up to 50 PSI. My car has the Bridgestones which are rated to 51 PSI max.
My grille is also blocked. It didn't seem to see much help in the cold weather, but I wonder if it helps in the cool weather.
The best tank average I have seen is Nash's at 48.0 indicated.
I think a 50 MPG tank (indicated) is achievable!
Many of my trips were over 50 MPG. My commute is an hour long at 40 miles each way. About half freeway and half arterial traffic.