How reliable are these things over 50,000 miles? Is this a safe buy and/or worth it?

http://sandiego.craigslist.org/car/280283221.html

 

The 500 series engine in a Mercedes is die-hard. It'll last longer than most of the car.

 

wow! 50k in 2 years. that's a lot
but i love those cars.
i drove an 03 with 30k miles with amg/keyless go and navi for under 60grand.
check it out by the mechanice and it should be good to go.

 

The 7 speed tranny in that car is very weak. I wouldnt buy it w/out @ least 100k warranty. My dad has an 05 and his tranny is horrible. The car has been in service over 20 times in the last two years, and he only has 24000 miles on it.