Originally Posted by bmorgan
I would be surprised if it had any aerodynamic value to it. I think the main reason for it is that the typical Mercedes owner would take offense to having any potential oil stain their garage floor.
+1
Originally Posted by JHM2K
I leave mine in place, but only because I'm once of those evil kids that likes to hit 135 every now and then.
I'm certain it serves a purpose at that speed. FWIW, Steve (32krazy) left his off and went for a speed run of 140+... he felt (and heard) a huge difference in wind.
So, mine stays on.
I am no aeronautical engineer, but I think the oil on the ground makes more sense than the high speed purpose. It may be different in Steve's SLK, but ask Ole Doc about his, he has seen some pretty high speed, and with some regulalarity, has had his off for a long time as well. I am in traffic a lot more than I am going 135 (and I do hit it now and again) so the known cooling effects far outweigh the aerodynamic gains, if there truly are any.