ABA test today was as follows:
I used the same 4mi. course that I did for my wheel covers. 2mi up, 2mi back, then averaged. Speed was 60mph, windows up, A/C off, radio off, fan on.
(Without Air Dam)
A1: 45.10mpg
A2: 44.45mpg
A3: 44.50mpg
AVG: 44.68mpg
(WITH Air Dam)
B1: 47.80mpg
B2: 48.25mpg
B3: 48.05mpg
AVG: 48.03mpg
(Again, without)
A1: 44.75mpg
A2: 44.6mpg
A3: 44.5mpg
AVG: 44.62mpg
I took the average of the closer results: 48.03mpg is a 7.49% increase over 44.68mpg!