I want to buy one off craigslist but I know nothing about the car.

My mother told me that it's a bad idea because parts would be expensive.

Is this really true?
And (besides millage) what should I ask about?

It can also run on veggie oil...


I just don't know where to start from...

Mercedes parts are very expensive. These cars also require a lot of periodic maintenance, per the Owner's Manual, which Mercedes assumes will be performed. If you are still interested, look at the maintenance log on the vehicle. Before buying, have a qualified diesel mechanic thoroughly check out the car. Focus on the engine and transmission.