For our 52nd Anniversary we went to a play at Niagara On the Lake ( in Canada) in our 2012 PiP. At the border crossing the Canadian customs agent commented on how quiet our car was as we rolled up to be inspected. Don't they have PiPs in Ontario?
Honestly my conventional Prius is just as quiet in such a circumstance. How many compliments have you gotten from US Customs? My experience is seldom very friendly.
I'll bet I know what he said when you explained the PiP is sometimes running all electric; . . . . . . turning on their place of origin - either they'll say "Hugh?" . . . . or, "AY?" .