Is there a release mechanism to be able to pull the glass up more so you can clean inside the interior cover. I've got a bunch of leaves and stuff on the cover which can't be reached by the crevice tool of the vacuum.

 

I haven't seen the sunroof on a 3, but most glass is held in with a few screws... so you can probably unbolt it to clean.
In addition to the crevace tool, tape a piece of garden hose to the end, that can be a nice range extender to get to hard to reach places.