"So if you buy, say, a plug-in Prius, which gets about 50 miles per gallon and drive it the same distance, you'd be using 36 fewer gallons of gas a year than with your old car. So it would take 9 years before your Prius will have “caught up” with your old car and saved enough fuel to offset the energy needed to make it.
I kind of doubt that was the standard of comparison that the mag used.
Even if they did, nobody unloads a fully functional car just to buy a more economical one. The math doesn't work out.
Anyway, since the HAH has gotten about 49 mpg actual from new, I'm pretty sure that a PHEV Prius would do a whole lot better than a trivial 50 mpg.