You must be used to Japanese cars. You coolant temp gauge is accurate, and reads the changes in coolant temp for real. Neat, huh? Most Honda, Toyota, etc. are non-linear to make you think your coolant temp is "constant."
It is not.
In your car, your normal temp range is from 80C or so to about 100-105C. Don't be too alarmed in hot weather with the AC on full if your temp gets slightly over 100C. In every MB I've owned, this was normal behaviour.
BTW, there is a huge amount of info in the archives. You might want to try searching...
1998 C230 "Black Betty"