My stock arm rest on my 2005 Mini S Cabrio has never stayed closed. There is no way to keep it from slidding easly back when you put your
arm on it. Is it supposed to have a latch to keep it closed? Or is mine
simply broken? It's realy anoying.

 

There is supposed to be a little piece of felt that provides a friction fit (there's a 'blade' of plastic that fits into a groove), but it doesn't work so good. The sliding armrest is a common complaint.

 

I have the same complaint with the '06 $300 arm rest. Every time you put your arm on the little bugger it becomes an elbow cup holder. I thought that was what it was for...an elbow stabilizer. I will try to add friction to the sliding mechanism to adjust this feature,