I'm currently at a crossroads, my 1992 400E has 210k miles on it and is in need of some maintenance, you could say all the usual stuff. What I'm debating is how far to go with this maintenance. Since I've had the car, for about 100k miles now I have NOT done anything to the timing chain, or anything to the transmission except for a fluid + filter change. So, there are two huge possible failures that could arrise at anytime, but no symptoms of anything bad about to happen. I'm thinking of doing a complete brake job which is a little pricey and wonder if it's worth dumping all this money into it if it might crap out soon. I'm wondering how much longer it can run without dealing with those two issues and if it's worth doing all this maintenance or just let to car go until it craps out and buy a new car. What would you do, and what maintenance would you suggest?

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1992 Mercedes-Benz 400E
2002 Mercedes-Benz ML500