To be honest, it looks weird. I mean in theory it would work. But in practical use it seems like there is A LOT that could go wrong. For instance, hitting something and it not sticking, the perp hearing something hit and then stopping to take it off, does it stick regarless of how clean the vehicle is/snow or rain covered, hitting a pot hole and then it falling off.
I mean if someone would use it I just wonder how reliable it's going to be.