Don't know how it goes with the Roadster but with the Plus 4 fitted with aircon there are two small pipes that exit from the side of the cabin air intake airbox in the gap between the airbox and the cover in the photos. When the aircon is running a considerable amount of condensation runs out of those pipes and under the box mounted above the footwell. From there some of the condensed water drips through the grommet above the footwell. In over 8,000 km we have yet to have the car out in the rain but I suspect rainwater would also drip through the same grommet. I intend to put a neoprene gasket under the flange of the cover but leave the lowest point open so that any water that does enter can escape. Given the cover houses electronic components it needs to be dry inside.
No aircon to worry about, just rain! As far as I can see, most of the water comes through the side louvres & arrives on said grommet. It then makes good progress through the grommet & on to the driver's ankle, via the throttle control. I found that some duct tape over the wiring loom/ grommet stopped the water, but didn't look very pretty, hence the cover.
Couldn't you extend the pipes so they discharge somewhere out of the way?
Ian
