I see a little bit of a wing resemblance that isn't seen in a base M4 model or a Competition model, it has been driven at mid-range speeds here where I spotted it in Pasadena (California), it really gives off that pre-production CSL prototype vibe...

Edit: Sorry I didn't take the photo on-time enough for a close-up shot, it only started to randomly appear while I was walking on the other side of the street. The red circle in this picture clarifies that this particular M4 has a bigger wing than usual.