Hi and welcome to the forum
Here's a list of possible E89 problems - http://www.z4-forum.com/forum/viewtopic.php?f=45&t=32132#p433856 but don't let this list put you off the Zed
as mine and others have been problem free
The only big worry I would have buying a older one is the roof mechanism ,if it goes wrong could imagine it being
very expensive to fix so make sure its got a good warranty