[MetroMPG]

That's going to be really good info to explain to other Metro owners what happens to this mount.

I still think another big contributor to the problem - maybe the biggest contributor? - is the drain hole in the floor immediately behind the front tire. It opens into a cavity at the base of the firewall which is also connected to the control arm mount. Water entering that drain hole from tire spray can pool in the mount, if there's enough volume.