Where was your 370 first registered from new, as it does seem to have some unusual features given your posts to date?
I ask that as I have seen and driven quite a few 370's and never come across one without the variable intermittent wiper speed as posted in the vid above.
Perhaps some pics of your car, inside and out, might help us to help you.
Edit:
Kinda of wondering it was first registered in Germany by a UK armed forces person (the tyres) knowing there are differing specs for countries around the world