I have the license plate transponder behind my nose cone and its performance is erratic -- I've gotten a few violations notices. It has also failed a few times at lift gate toll booths, which presents a real problem. So I've switched to the windshield transponder mounted to the right of the rearview mirror stem on the black dots, as Tesla has advised. Don't yet have enough experience with this mount to determine its effectiveness, but I'll report back when I do.