I used Google location history to map our truck's mpg during our move from Texas to Nevada. The truck was pulling a 16' trailer packed to the gills.
The mpg took a hit in Texas most likely because the speed limit is so high and the terrain actually pretty mountainous before El Paso. In Nevada we hit a big windstorm and were lucky to get 5 mpg. It was pretty windy in Southern Arizona as well.
Final product:
