When it comes to China, the issue is more than academic for the Detroit automaker. More G.M.-branded cars are now sold in China than in the United States.
The potential bans call into question G.M.’s plans to tackle the next generation of new energy vehicles. G.M. has focused much of its efforts on developing plug-in hybrid vehicles. These cars, like the latest version of the Chevrolet Volt, have batteries that can allow them to travel 100 miles or more per charge.
But they also carry gasoline engines and gas tanks that then allow them to travel several hundred miles farther. The announcements of Britain, France and China could be read as possibly prohibiting plug-in hybrids because they call for cars not to emit any greenhouse gases, which internal combustion engines produce.
Many other automakers have a stake in the issue of how any ban might be written. Even Volvo, the Chinese-owned Swedish brand that has taken the lead this year by saying in early July that it would stop making traditional gasoline-powered cars in 2019, still plans to rely heavily on hybrids instead of trying to jump entirely to battery-electric cars.
Ms. Barra “is right to be cautious, because even if you look at Volvo’s strategy, it is not 100 percent electric vehicles,” said Yale Zhang, the managing director of Automotive Foresight, a Shanghai consulting firm.
Plug-in hybrids may prove popular in places with a lot of intercity driving, like the United States, G.M.’s home market. Internal combustion engines also provide a lot of power for challenging tasks like towing a boat on a trailer.
Geopolitics play a considerable role in the issue. China is unenthusiastic about plug-in hybrids because most of the patents are owned by foreign automakers, particularly Japanese multinational companies. Chinese carmakers have been stronger in battery-electric cars.
China issued draft regulations in June to require all automakers to begin selling large and ever-growing numbers of so-called new-energy vehicles over the next several years. Those draft rules, which would reward automakers for the number of new-energy cars they make, emphasize battery-electric cars over plug-in hybrid electric cars. Global automakers have been lobbying the Chinese government to loosen the rules before they are finalized.
Electric cars may have more appeal in China anyway. Major cities are linked by high-speed rail, and long drives between cities have never really taken root here the way they have in the United States and Europe.
G.M. is particularly vulnerable to any broad divergence of policy between China and the United States. G.M.’s various joint ventures with Chinese automakers together sold nearly 1.8 million cars in the first half of this year, while G.M. sold 1.7 million cars and light trucks in North America during this period.
G.M.’s goal is to create cars that meet common needs across markets around the world, using a combination of electrification, internet connectivity, self-driving car technology and ride sharing, Ms. Barra said.
“G.M.’s vision,” she said, “is a world with zero crashes, zero emissions and zero congestion.”