After seeing the video I agree with Collision Detection that this robotic proboscis is not entriely convincing as a dog tail. This is despite the presence of a black lab in the video. And anyway - as a sign there are problems with a wagging tail, given the ambiguity.
That wonderful tail can say; "I am interested in that, I am challenging that, I will dominate that, I feel very confident right now, I am relaxing now, I am scared right now and feel threatened, I am confused right now and don't know what you want me to do, or, I will protect you now and I will be aggressive...source
I remember Doug wagging his saying I will dominate that as he encountered another male dog in the park -a preliminary to dog rage. Perhaps the car could have a set of hackles to switch into unequivocal aggro mode.
And Bronte is a dog that has the submissive tail wag that in traffic wouldn't be saying 'thanks' as much as 'help'.
I want to enter this pack so please don't hurt me. I am willing to be submissive to the Alpha tanks.