I have one, and as said in another post someone drove into my fender and headlight. the car has a bad paintjob, an engine with a bad cylinder, the interior is soso with a rear seat of a 300 cd because of the horsehair problem and still I want to keep it. they drive amazingly nice, handling is superb. and it has the old looks, considering the 116 dates from the early seventies. and then it's got the 5 cylinder turbo engine! I'd go for it, even rusted. just have it for a while and enjoy man. depending on how bad the rust is you can decide to put money into it. the servo can be bypassed by removing the whole unit and putting in a cheap inline valve to control waterflow to the heatercoil. very manual control!
goodluck
henry.