For 1995 E320, the coupe is about 440 pounds lighter than the cabriolet ...

coupe: 3,550 lb
cabriolet: 3,990 lb

http://www.mbusa.com/overview/1988/E300CAB.do?modelCode=E300CAB&preModelCode=E350W&preClassCode=06_E&preAccClassCode=E&overviewMenu=e-class