Nice time for an update. We've had the Honda Clarity a couple months now. We charge at home on normal household current, and use the hybrid gas motor on highway trips. We haven't seen any discernable difference in the electric bill. I have noticed that as the weather cooled, the car's electric range on a full charge has diminished from the advertised 47 miles to just 40. It also goes through the first few pretty quickly, likely due to cabin heat, seat heat, and just more 'rolling resistance' in its folder weather. The range is still plenty adequate for daily needs running around town.
It still gets 45+ mpg on gas on the highway, so overall, we are at nearly 70 mpg. It would be more of we didn't have a second home 130 miles away, and no charger there.
For where we live, considering the lack of electric charger infrastructure, this plug -in hybrid (or a Chevy Volt) are the only game in town.
Jim