Age is starting to take their toll on these. You will need to be vigilant and patient to find one that has not been "let go" by the owner over cost of parts vs. car's worth. You find a good one, it'll be as reliable as gravity mechanically. Most of the 123 cars will need some kind of A/C work, and the 300's have much more complicated HVAC systems than the 240D's. If you find one that needs little work, you will have years of driving enjoyment. I replaced a radiator yesterday in my 240D, as well as a glow plug. The job is so easy that I was in a GOOD mood when I was done.