yep maybe had the same problem with my p38 and it was the drains for the sunroof it is easy to find out if iam right you will have to take the two small parsel shelfs off and the panels underneath them where the back of rear seat locks into the clasps in the parsel shelfs,right close to the clasps there is a join in the sunroof drain pipe and mine had fell apart as they are only pushed into each other ,what happens is when the pipes fall apart the water runs under the carpet and straight into the spare wheel hole will take you one hour max good luck :dance: