The argument to not spend the extra money on the PHEV misses one important point.
The price difference pays for an electric drive train which is quiet, powerful and fun to drive in the city.
I challenge anyone here to test drive a Chevy Volt when the battery has been charged full overnight and scoot it around in the city. It's a hoot when running fully on electricity.
People spend money on leather seats, sunroofs, audio/electronic systems in their cars, all of these extra's are compelling for their owners.
My take : The quiet, low noise, low vibration electric drive system is a luxury + performance + efficiency option that is worth the money.