“That puts us in competition with the both the E.U. and the U.S.” Mr. Palmer said.
The British government says that it realizes the importance of the car industry and is working on assuring its future.
“We are very focused on making sure” Britain has electric vehicle manufacturing, Jeremy Hunt, the chancellor of the Exchequer, told a business audience in London on Wednesday.
What specifically worries Stellantis and other makers is an import regulation that falls under the so-called Rules of Origin and is set to take effect next year. Under the rule, at least 45 percent of the value of the materials of cars exported to Europe must come from either Britain or the European Union if the makers want to avoid paying duties of 10 percent — a stiff penalty in the highly competitive car business.
Stellantis says that it cannot meet these standards because of rising costs for raw materials among other issues. It says it wants the British government to negotiate a postponement of the rules until 2027.
The concerns are not limited to Britain. Stellantis forecast that there will not be enough battery supplies in Britain or Europe to meet the ambitious targets of governments for shifting to electric vehicles over the next few years.
Mr. Wells said the situation put a damper on the auto industry across Europe. “How,” he asked, “can Europe continue to supply into a booming electric vehicle market while simultaneously insisting on these local content rules?”
Eshe Nelson contributed reporting.