We have a BMW E36 323i with a fully automatic roof. This unlocks the top, lowers the roof and covers the folded roof with the built in tonneau cover. The windows lower themselves a few inches as part of the process, then go up again. All this at the press of one switch. This is really convenient, but cost a few bob to fix when it played up a couple of years ago. The Z3 semi automatic system seems a waste of time to me when you have to unlatch and install the tonneau cover manually. Our manual Z3 roof is easy enough to operate and there is little to go wrong.