Given how questionable / blinkered Burks view of many things are I'm not sure it would make much difference. ;-)
One thing I will bring in when I'm PM (as a general strengthening of the general 'obscuring your vision' legislation) is that anyone with anything dangling from the interior mirror can be dragged to the gutter and shot and their body hung from an overhead gantry as a form of ironic warning to others (or maybe not as it could be distracting). ;-)
WTF would you want your car smelling of pine and a cardboard tree swinging about in your car, especially in your field of view?
Cheers, T i m