Feierstarter, first there are several German owners of the 5 speed M3W on this forum alone. Tyres are not an issue.
I owned mine for 2.5 years and covered 9000 miles with 100% reliability. Having said that there were problems with earlier models although most have had the defects attended to by now. 2014 saw many improvements although there were still issues particular with the Centa drive train rubbers disintegrating. An engineer enthusiast Phil Bleazey on this forum has come up with a range of solutions to improve both reliability and longevity.
S & S no longer build the engine and spare parts will become difficult in the near future. Given the enthusiasm for the model and numbers on the road my own opinion will be that further solutions and work around's will be found to keep them running.
This vehicle is a car no matter what the politicians choose to call it. In some parts of the US it's classified as a motorcycle though requiring that tight headlamp spacing needs to be complied with, adding to dangers of using such at night. It appears this blatant stupidity is less common in European countries though. I would expect to be able to use the M3W anywhere in Germany that more conventional cars are. Perhaps not on narrow tracks with a central drain though
I tried to avoid using mine in forecast bad weather but inevitably you get caught out. I remember driving in torrential rain but the engine didn't miss a beat. Even whilst moving though the shape of car does suck in rain and seat squabs need to be removed and floor mopped out after a journey in heavy rain. Water proofed leather helps here.
I'm sure other current owners, hopefully some based in Germany will be along to give their opinions. The fact that prices of this now discontinued model remain very robust says a lot.