According to Wikipedia, Chevrolet has sold a little over 15,000 Volts in the US since they started producing them in 2010. The world wide sales numbers are a little hazier, but if I had to guess, the total number of these plug-in hybrid electric vehicles in service today is probably around 19,000.
I saw my first one in the wild today, in white, while not necessarily attractive, it is certainly not ugly either, as it passed by me on I-20 in Columbia.
Somewhere just east of New Holland, the Purple Whale, windshield wipers slapping back and forth, passed the 19,000 mile mark.