Consumer Reports listed (in 2002) that the 1996 model C220 to be one of the most reliable used cars one could buy! That says a lot. My personal experience has to amplify that. These cars are now 8 years old and mine is, literally, like brand new with 107K on the clock. They seem to be bulletproof, but who knows what the future holds. I'm betting on continued reliability. As an added benefit the car gets 35-36 mpg on the highway which is not too shabby!
If I would recommend a MB for your daughter it would be this one!

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1996 SL320 97K miles
1996 C220 130k miles
1992 500SEL 170k miles <---sold
1986 300E 216k miles <---sold