To answer my own question: dunno. But the technology has a lot of promise. The Wikipedia entry on plug-in hybrid vehicles” is a thorough and well-cited background on the technology and its potential. In particular, of course, I am interested in the vehicle’s intersection with the electric power network:
PHEVs and fully electric cars may allow for more efficient use of existing electric production capacity, much of which sits idle as operating reserve most of the time. This assumes that vehicles are charged primarily during off peak periods (i.e., at night), or equipped with technology to shut off charging during periods of peak demand. Another advantage of a plug-in vehicle is their potential ability to load balance or help the grid during peak loads. This is accomplished with vehicle to grid technology. By using excess battery capacity to send power back into the grid and then recharge during off peak times using cheaper power, such vehicles are actually advantageous to utilities as well as their owners. Even if such vehicles just led to an increase in the use of night time electricity they would even out electricity demand which is typically higher in the day time, and provide a greater return on capital for electricity infrastructure.
There’s a lot of promise in using PHEVs essentially as distributed mobile storage units. See also this excellent IEEE Spectrum article on the extent to which PHEVs can contribute to grid stability. Depending on how they are used and on how their interconnection happens, there are conditions in which they can destabilize the grid too … but that’s where all of that smart-grid remote sensing and digital switching and dynamic reactive power capability becomes useful.
Think about it.