criuse

I recently changed my 2004 w203 230k for a 2007 w211 c220cdi, today i went down a hill with cruise set at 30 mph (there is a camera on the hill), and the car slowed as if the brakes seemed to be applied at over 30. This did not happen with the W203, I always had to brake to slow, I have noticed...

How simple/hard is it to fit cruise control to my 1992 300sl is there a port I can just plug into or would i have to link up everything. cheers Pete:D