Here is one from the 2012 season. It's Insight Racing that looks like a police car. They also had a #19 running in the GS class that was kind of the opposite colors so they looked cool running together.
Sorry it's not a SLS skin. Only seen one SLS and that was Tim Pappis's SCCA World Challenge car this year at Road America. It was pretty much in the way but other than the Bentley Continental GT from Dyson it was the coolest looking car.
BMW 1M Grand Am ST Insight Racing 18 2014-08-31
BMW 1-Series Continental Tire ST Insight Racing Skin