I finally received my personalized plates on Friday, about a month after ordering them...
My rear plate (in AZ only rear is required) now reads:
HIGHMPG
I got my first comment Saturday nite at the drive-in movie. The guy parked next to me asked about the Hybrid, what my MPG was, etc. Did not ask about a plug, so points for that !!
He said he was mildly interested in replacing his 12 year old Toyota pickup and I told him to go for it !!!