GM is simulating tests to make sure the lithium-ion batteries last 10 years, Posawatz said, as well as testing battery performance in extremely hot and cold climates.
"We're further along, but we're still quite a ways from home," he said. "We're developing quite a knowledge base on all this stuff. Our confidence is growing."
The other area of new technology, switching between battery and engine power, is proceeding well, he said, with engineers just fine-tuning the operations.
"We're very pleased with the transition from when it's driving EV (electric vehicle) to when the engine and generator kick in," he said.
GM also is finishing work on the power cord, which will be durable enough that it can survive being run over by the car. The Volt, he said, will have software on board so it can be programmed to begin and end charging during off-peak electrical use hours.
It will be easy for future Volt owners living in rural and suburban areas to plug in their cars at night, but even Henderson recognized the challenge urban, apartment dwellers, or those that park their car on the street might have recharging the Volt. There could eventually be charging stations set up by a third-party to meet such a demand, Henderson said.
Chrysler Group, Ford Motor and Daimler are all developing plug-ins and electric cars, and Toyota Motor is working on a plug-in version of its gas-electric hybrid system. Nissan Motor announced last month that it would begin selling an electric vehicle in Japan and the U.S. next year.