Funny (or not so) topic of familiarity to me this one.
With smart Roadsters (Leaksters) not the engine one but another ecu the SAM unit was sited under the wiper tray which had a habit of leaking ( when it filled with water due to blocked drain which was substantial in diameter) and poorly assembled pinched seals did not help, this sam unit is inside the car just above the drivers knee it effectively is a fancy fuse box come input output unit.
People have taken to protecting the multiple circuit cards inside with various coatings as it's not only direct water intrusion but condensation from a saturated wet insides (various paths for water to get inside the cabin on none sorted roadies)
My advice if you are at all likely to use a car in the wet or even park it in the wet is to be proactive where the electronics are concerned and protect them before it becomes an issue.
We do see quite a few Mogs advertised as "garaged and never driven in the wet" it's a car it should function okay in the wet it's not my older brothers first mini he had where the wiring had gotten that damp it fell apart in his hands.
Maybe expected in the 70s not now though
