watch out for? In addition, I was told that maintenace for Mercedes S320/S500 is very expensive (e.g. suspension maintenace, etc.) and I would like to know what I am getting into. When I buy a used S320, what should i pay particular attention to?

Check the AC big time. I got a neighbor that has a S600 and the AC was bad all of the time. You may have to have it checked by a professional mechanic to be sure.

The mileage and the condition. Make sure the owner has had a recent oil change, transmission flushed to make sure the is no oil on it, wheel alignment, good tires, Good brakes, all the door handles work and don't need to be replaced, rooters are in good condition and make sure that you heater and air conditioner work. Ask the owner for all the paper work they have on recent or any jobs done to the car.

I bought a used car and had to figure this stuff out the hard way.

ball joints!!!!!!!!!!!