I have purchased a Mazda 323 which has approximately 90k km on the clock. While driving in the rain some water will come in above the brake pedal, approximately 5 or 6 drops during an average local journey (~10 km). A mechanic has said that the firewall has deteriorated and will cost a lot of money (~AU$800) to weld up.
This seems unlikely to me, however I am open to correction. Does a car’s firewall deteriorate enough over time to allow water to leak in?