I believe that you would want the plug in hybrid to increase the vehicles ability to operate only on electric power for a greater distance, and at a higher output (bigger motor) without the gas engine. The reason the current crop of hybrid don't have a plug is based on consumer research that indicated consumers had no interest in plugging in a car. The plug would make the hybrid resemble more a traditional electric car with an on-board electric generator. You could have the bigger electric motor, bigger battery capacity, and cheap electric grid power to motivate the vehicle w/o the gas engine for longer distances. You would also have the on board electric generator and gas engine drive that would allow for much longer trips than the electric alone could achieve. My other half had an electric car for years, and the monthly electric cost was 20-30 bucks a month. With the current price of gas, and if you drive alot, you could recover the hybrid cost fairly quickly. At todays prices, if you saved couple hundred dollars a month in gas which would be possible with a plug in, then the system would pay for itself in a fairly quick time period. When toyota talks about a hybrid getting 100 mpg or more, the wall plug is the connection that will allow them to achieve this sort of milage. I read someplace recently that Rick Wagoner now thinks it was a mistake to stop producing the EV-1. When you look at the current gas prices, combined with the development that has occured in these first generations of hybrids, added to the significant savings that the wall plug can provide, then it seems pretty obvious why Wagoner thinks dropping the EV-1 was a mistake. The path of the traditional electric and hybird are merging. That said, GM probably more experience than any other automaker in commercializing and manufacturing a traditional electric car from their experience with the EV-1. If gas prices continue to increase, I believe that the cost of gas will drive at the very least a low end hybrid system on par with the Generals BAS system onto all but the lowest end vehicles. The road to hydrogen probably includes a drive down the hybrid highway.