In the S1, water from the rear wheel wells is sprayed into the engine compartment floor. From there it’s free to flow up the sides along the chassis. We all know what this means to the state of any original chassis!
In a normal shower it gets in and then slowly evaporates or finds its way out. However, if you are experiencing days of long distance rain days, the level builds up and it seeps in through the seat belt mounts and in under your seat squab.
I’ll be having the squabs redone with plastic, rather than fibreboard, bases.
We S1 owners should get together and start the Soggy Bottomed Section of this list.