Some people just aren’t satisfied with going weeks between fill-ups in their Priuses. Some want to go months!  In the Christian Science Montior article Plug-in hybrids: a here-and-now alternative, Mark Clayton reports on homebrew efforts, to add batteries and a charger to your Prius and get a 50-60 mile charge each night:

One auto critic who tested a plug-in Prius recently reported that in normal driving, not trying to go easy on the throttle, he would still have to fill up the tank just once in 5-1/2 months.

This doesn’t seem like low-hanging environmental fruit to me, but clearly it appeals to some!  Where there’s a market, a vendor will emerge:

Edrive Systems, a private Los Angeles company, plans to offer by early next year an aftermarket kit that converts a Toyota Prius into a PHEV. Target price for the under-the-hood makeover: About $12,000.

But this seems to represent the extreme of a more broadly-based level of interest that is leading other manufacturers (such as Volkswagen), to follow suit.  ‘Bout time!