I bought a 1999 C230 a month ago it has 63k miles. I noticed the car seem to shake and it feels like you're driving on a rough road. I try driving my other car, and it seem smooth on the road. Is that mean that I need to replace the 4 shock absorbers on the car or should I look at other area? Is it difficult to do it yourself? Any comments are welcome.
Thanks in advance.

Bump - with a comment. It seems almost inconceivable your car would already need shocks. If it has stock suspension parts, wheels, and tires - you should have an excellent ride. Ride, though, is a highly subjective judgement, and is useful only if described in high detail.

E.g., do you notice a rhythmic vibration on smooth roads? At engine frequency or tire rotation frequency? Is the ride smooth except it reacts harshly to evey little bump? Do you feel anything in the seering wheel? Seat of the pants? Etc. The more informtion you give - including hat specifically you are comparing it to - the more likely you will get a helpful response.

Steve