Go to paintscratch.com and you can see a list of the color codes both in 3-digit and 4-digit. I believe 3-digit codes are typically used for chassis door cards, and 4-digit codes for part numbers/trims/etc.

Here is what comes up for the MY2000 C-Class.

Black Clearcoat 040/9040
White Clearcoat 143/9143
Black Opal Pearl Clearcoat 189/9189
Obsidian Black Metallic Clearcoat 197/9197
Calypso Green Metallic Clearcoat 279/6279
Aquamarine Metallic Clearcoat 341/5341
Azure Blue Pearl Metallic Clearcoat 366/5366
Bordeaux Red Metallic Clearcoat 567/3567
Magma Red 586/3586
Desert Silver Metallic Clearcoat 693/1693
Brilliant Silver Metallic Clearcoat 744/9744
Tectite Gray Metallic Clearcoat 753/7753
Aspen Green Metallic Clearcoat 891/6891
Midnight Blue Clearcoat 904/5904
I know if you try some different google terms there are some sites that have more detailed info.