Considering a Mercedes Benz 300 as my First Car?

So I've got about $5000 to spend, and everything I've read about the 1980's Mercedes is all about how they're good to run even past 500,000 miles. (if they're well maintained)

What exactly does that entail? I've never owned a car, and I don't know if a car like this needs different regular maintenance than, say, a 2002 Honda CR-V.

What's everything I need to know about this car? Because I'm seriously interested in it. I heard they're very easy to do work on yourself. Is it easy to learn how to work on one if you've never worked on a car before? I've got plenty of time to learn.

And the big question is since Mercedes-Benz cars supposedly cost more to maintain… About how much can I probably expect to put into the car yearly for that kind of stuff?

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