SHANGHAI >> Cars should run on gasoline for a little while longer.

So argued Mary Barra, the chief executive of General Motors, who today cautioned against the growing trend of officials in China and a number of other countries making plans to phase out sales of gasoline- and diesel-powered cars.

Speaking in Shanghai, Barra said her company was making a big push to develop electric cars but that consumers, not government dictates, should decide how cars are powered.

“I think it works best when, instead of mandating, customers are choosing the technology that meets their needs,” she said.

China this month joined other countries, including Britain and France, to say they will eventually ban sales of gasoline- and diesel-powered cars. Unlike those two countries, which said that they hope to halt sales in 2040, China has not set a date.

Targets set more than two decades in the future, which is roughly four generations of car technology, are to a considerable extent symbolic. But automakers make a lot of long-range plans and are sensitive to how government targets may influence consumers’ preferences.

When it comes to China, the issue is more than academic for the Detroit automaker. More GM-branded cars are now sold in China than in the United States.

The potential bans call into question GM’s plans to tackle the next generation of new energy vehicles. GM 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.

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.

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.