Mercedes C230 through C320 from 2001 to 2006.

Aftermarket fans will require Hooziewhatsits controller (in the Moparts Products section). A direct 12 V line will burn them out quickly. Some factory fans can take a direct power input without a controller but that makes them run at insane speeds full time.
Factory fans are quite expensive.

We went through great lengths to test factory Mercedes vehicles and find out what kind of signal they used to power the fans.