The New York Times > Business > Hybrid-Car Tinkerers Scoff at No-Plug-In Rule: " If you were able to plug a hybrid in overnight, you could potentially use a lot less gas by cruising for long stretches on battery power only. But unlike purely electric cars, which take hours to charge and need frequent recharging, you would not have to plug in if you did not want to.
'I've gotten anywhere from 65 to over 100 miles per gallon,' said Mr. Gremban, an engineer at CalCars, a small nonprofit group based in Palo Alto, Calif. He gets 40 to 45 miles per gallon driving his normal Prius. And EnergyCS, a small company that has collaborated with CalCars, has modified another Prius with more sophisticated batteries; they claim their Prius gets up to 180 m.p.g. and can travel more than 30 miles on battery power. "

Is this cheaper than gas!!! hmm... I guess my electric bill would go down, but I can just turn off my computer at night. That would keep my electric bill at the same rate.