I see at least 20 every morning on my 30 mile commute to work from OC to LA. Funny enough, there was 6 of us in a row monday, one behind the other until a Volt decided to join the party.
I got a message that my charge door was open after I left it parked, unattended for awhile. I wonder is someone wanted to siphon gas, or were just curious what could possibly be behind a filler door on a Prius.
For the first time I came out of the motorway service station to find another PiP next to mine, charging up. I was so excited I took a picture...
After slowly learning to recognize the subtle differences of the various generations and non-PiPs vs. PiPs, I realized the other day I was the second in a line of 3 PiPs. And we were not: in an HOV lane on a freeway|highway during a commute time or anywhere one might most reasonably expect multiple PiPs. (After we made our left turn together, the other 2 "raced off" against each other (sorta..) as I turned into a supermarket..)