Hybrid-Car Tinkerers Scoff at No-Plug-In Rule

“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.

NYT