[Mango]

^Yeah I dunno. It's possible the net effect, if any, would result in higher overall drag as you might disrupt airflow down the side of the car causing turbulence inhibiting clean air separation at the rear. Not to mention you will probably create some really nice mud streaks on the side. Not sure though?? Lookin forward to your testing

If you really want to make an aero difference with the fenders, round off the edges where it meets the tires =p