I own a 1996 S420...I'm the second owner, but have owned it since 1998 and bought the car while it was still under warranty.
If the car was serviced by an MB dealership, then they should have all the records. Maintainence records should be found stamped in the owners manual.
The W-140 is a great car, but sometimes a bit tempramental...like most cars.
Some things to watch out for:
1. Change the transmission fluid every 50 - 60k instead of the factory 100k. If you don't have a record of a change from the previous owner, then I would have it changed now.
2. Make sure that all the pushbuttons on the climate control system work, if not...have the dealership you bought it from change it if under some 30 day warranty. This is a $680.00 part.
3. If you are a classic DIYer, parts are less expensive if you purchase them on the web. Fastlane (on this site) is a good source as well as some others.
4. The only nasty item on the repair list is the A/C evaporator. Not to scare you, but it is one of the most disturbing problems that I have experienced on my Benz. Replacing it is very expensive, and it's not because of the parts cost, it's the labor @ 20 - 30 hours. Mine began leaking @ 100,000 miles. If you have a 30 day warranty, have the AC checked for leaks. One of the telltail signs it a red light that won't turn off at the EC button on the climate controller.
I have found that the people who participate in this forum are dedicated hard core MB owners that have tackled just about any problem that I've come across. There are also some MB mechanics on this site that are very helpful. Information on this site is easy to find using the search engine...type in W140 and a bunch of information will pop up.
Enjoy one of the finest automobiles on the road. There's nothing like em...