The ~600-unit M3 CS is treated as a special limited variant with CS-specific muffler and softer springs than the ZCP, commanding roughly $50k-$75k in these threads; commenters note it is frequently and mistakenly conflated with the Competition (ZCP) package in listings, which suppresses awareness of what a real CS is.
M3 CS: rare send-off variant, often confused with ZCP
BMW F80 M3 (2014-2018) · variant