if its really windy it gives a little whistle, with out wind u cant hear anything, but then i haven taken mine off over 2 years and i have been on some long trips. it does kill ur mpg a little. just from my experience

 

Just drove to SJ and back this weekend, filled up right outside the freeway, and averaged 24.1 mpg the entire trip.

COBB AP said 23.3 mpg, while the dash average read 24.6 mpg. True average was 24.1 (total miles traveled / gallons require to refill)

I set cruise to 70 the entire way

 

i see ur car almost every day on hwy 50 in the mornings