The battle over the future of hybrid car architectures rages on. General Motors, along with many experts, are betting that the future of hybrid cars will largely belong to plug-in series hybrids. These cars contain both a gas motor and an electric motor. The gas motor, however, does not propel the car. Instead, it exists only to recharge the battery, which powers the electric motor and by extension the car. The cars, also called extended range electric vehicles, can go further on a change than pure electric cars and cost less than electrics. The Fisker Karma, coming in late 2009, and the General Motors Chevy Volt, coming in late 2010, are series hybrids. On a full tank, the Volt will go 640 miles. End of story? No way, says Andy Frank, the soon-to-be former UC Davis professor and plug-in advocate. The complexities of the series hybrid architecture adds costs, he said. That's why the projected price of the Volt has climbed from $30,000 to $40,000. "They think it (series hybrid) is cheaper but it is not. In order to get the same performance, you have to get a much bigger electric motor," he said. "GM is now struggling with that." Frank's preferred solution? A parallel hybrid, like the Toyota Prius, in which the gas and electric motor power both propel the car, either in tandem or alternatively. Frank, however, also wants to bring the price of parallel hybrids down. To do that, he started his own company, called Efficient Drivetrains. The company is working with car dealers in Europe and Asia to come out with hybrids using his components. (There is more in our interview with Frank on the video on the front door.). Frank is resigning from the university because of the challenges of doing both. Frank predicted that plug-in hybrids based around his technology will cost about the same as conventional cars in four to five years. That, however, assumes that manufacturers produce 500,000 or more cars a year. Other academics are also looking at split hybrids, in which the gas engine and electric engine provide distinct separate tasks, i.e. the gas engine runs the back wheels and the electric engine runs the front ones. Whatever the architecture, Frank says he is a fan of plug-in hybrids over all-electric cars. "The problem with electric cars is that they can't be charged quickly," he said. "With plug-in hybrids, when you don't have electricity, you can drive on gas.