Anyone have any good ideas why there would be lots of water on the drivers rear floorboard of my 01 C320? It definitely has nothing to do with coming from the outside from rain or anything else because it happens even on sunny days.

 

check your AC drains might be disconnected/plugged

 

I know, got the same thing. It's the rubber plug that has rust around it. I take out the plug, try sanding it down, a month later the Zbar and under coat foamed up again!