The plastic under bumper didn't fare too well.
I basically stole big dave's idea for an air dam when I came across a thirty some inch wide piece of smooth rubber conveyor belt.
With the 30 inch tires that were on the car at the time, the new air dam was 2 inches from the road surface. This did cause quite a bit more contact than with the plastic which wore substantially until it was roughly 3.5 inches up and then it just broke.
I have since changed over to a shorter tire and the air dam is even closer which doesn't seem to be any more of a problem, but I have been strongly contemplating Freebeard's comments on post #10 about a central jet.
If you check out this link with high definition photos of a later model c class, you can see that Rennsport has implemented a front bumper that, to me; looks like what Freebeard has described.
https://www.mercedes-benz.com/en/ats...t-tourenwagen/
I also really like the fender venting behind the front tires. I was very much considering a total radius of that edge as listed in the wiki and on the dodge m4s prototype
https://www.allpar.com/cars/concepts...-Ackerman.html
I'll get you guys some photos of the air dam in it's current state and try to ms paint my wanted mods to get some feed back before I take the knife to it.
I also removed the factory plastic rocker panel cover and made a side skirt of the same rubber conveyor belt. I need to fabricate a block off for the hole I made for the exhaust that I had for a short time just in front of the rear wheel, so forgive me that atrocity.
photos added to post #1