That's either a 2.3-16 or the later 2.5-16. It was the platform that was used to return Mercedes back to closed circuit racing. The 2.3-16 was the only one brought to North America, the 2.5-15 wasn't ever "smogged." With a twin cam head developed by Cosworth Engineering and unique body kit and spoiler, it's quite the departure from Mercedes of the late '80's and is sometimes called the "Banker's Hot Rod."