YMMV, and since I do not have one (nor the inclination to buy one), I can only assume that the hype and stories were erroneous. I was basing my comments on this (from the horses mouth I would assume) and this
Last paragraph in your link "from the horses mouth"
The 240-v charger is optional as the Volt can be recharged using the standard 120-v wall socket charger that comes with the car. This would take about ten hours.
The optional charger described in the link would charge a depleted battery in about 4 hours.