I've seen quite a few here in Pittsburgh. Or maybe its the same ones?
I've seen many, many volts, though. There's one with the plate WATTUP. I've seen 2 Leafs.
Also saw a Fisker Karma once in the Strip District.

They are TINY.
Come to think of it, I've seen lots of odd cars in the Strip District. Stretch limo pickups (?), Bentleys, and the occasional not-yet-accounced car in this weird zebra-looking cover to try and keep you from figuring its shape...