Peter,
my 3.7l roadster with spare or without does the same. Far worse than the S1 & previous trads. I think it is the front undertray & rear panel for the fog & reverse lights.
John
My Morganeering started with a 2011 Plus 4 which seemed to get as much rain on the inside of the windscreen as out when roof down in heavy rain. Other than that it was OK. I replaced that in 2017 with a 3.7L Roadster which was pretty much the same. Both had spare wheels. I now have a 22MY Plus Four which sucks all manner of stuff into the car. It's also the first time I have had muck coating the sidescreen bag when on the luggage rack. I am told this is down to the smooth underside of the CX chassis compared to the trad. Perhaps it needs a diffuser?
John
