you could do the outline thing but wouldn't suggest it, if someone really wants it they'll just chip your paint with a flat head screw driver. but most of the time i don't bother for them cause i only use my fingers and fingers don't fit in those outlines. or you could check out the audi emblems.. either they're too big to rip off or they've got a trick to get it to stick.
another way is to get an emblem with screws and you stick it through the holes.. giggity. and go to the other side, probably take off the hatch plastic panel cover thing and then twist the nut in to lock it, and if you want it to stick even more.. add some super glue/residue/double sided tape or w.e. so now.. the only way to get it off is to cut it off or take your hatch or something lol