I love the look of the standard Cooper – in some respects more than the MCS. I like the shape of the bonnet and the chrome accents among other things. But there are several areas where the design details of the MCS are simply superior. Things like the chrome gas cap and the the S-lite 17″ wheels are fantastic additions to the car. But the piece that I've really grown to appreciate lately is the MCS side skirt on the lower side of the car.
The first thing most people notice about it in comparison to the Cooper's version is that it buldges out from the body giving the car a more muscular look. But beyond that I've found out It also offers more protection from small rocks that can get kicked up by the front wheels.
After just under a year of ownership I've found my Cooper's side sills to be riddled with small pit marks from from these stones that get kicked up (some if that is probably due to my 215/17/45 sized tires). It's been a real annoyance that after a wash the rear part of the side skirt looked like it had a light grey glaze over it due to all those small scratches.
So my solution was to find some side skirts (thanks David!) that had come off an MCS that was getting the aero kit. Installation was a little tricky but after a couple hours with little or no instructions we managed to get them fitted to my Cooper (thanks Steve!).