The drive for us to get from NE Tennessee to the West is crushing. It is do incredibly boring. That makes it hard not to want to drive faster, but higher speeds really do cripple mileage. The single thing we discovered that really makes a different is mountain terrain versus flat land.
We live in the Appalachians so we have a lot of ups and downs, nothing like the Rockies, but we pick up about 1 mile per gallon when we are in Florida.
Mileage has a lot of factors of which aerodynamics are but one of many.
Steve and Andra
2012 F350 6.2 gasser SRW LB
Fab Fours front and rear in case we run into a rhino
2019 Northstar Laredo SC