Very close to destination for Road Trip

Today in Dothan Alabama.  We are two hours away from the end of the Road Trip.  After yesterdays over doing it today wa a much better day of 331 miles.  Total miles as of today is 3098.  Miles per gallon have varied from 9.2 to 11 MPG.  Variables are mountain slopes, head wind, and truck speed.  I think but am not going to do an experiment to prove it that the wind shield I built adds about 0.5 MPG.