Hmm, 1.5 inches is a lot, so
 

Hmm, 1.5 inches is a lot, so mehbe the mirrors make a bit of difference, eh.

to clarify - didn't mean to
 

to clarify - didn't mean to imply the 2 actions (lowering vs removing a mirror) would have equal reduction in drag. just equal reduction in frontal area.

if i had to guess, i'd say the drag reduction would be greater from lowering vs mirror removal. it would reduce not only the amount of surface area facing the wind, but would also the amount of air going under the car (an aerodynamically dirty area).