For BMW, Tesla, and other global automakers whose future is ever more dependent on China’s burgeoning market, any gains from lower import tariffs this week will likely be short-lived — thanks to President Trump’s trade war.

After decades of pleading for easier access to the world’s biggest car market, manufacturers finally saw duties on overseas imports almost halved to 15 percent on Sunday.

But the reprieve for producers of those models — if they are built in the United States — is set to end on Friday, when a retaliatory 25 percent levy makes them more expensive.

Trump’s tit-for-tat trade squabble with China threatens to undo years of lobbying by carmakers and drag Europe’s leading luxury brands into the fray because of decisions that were made when global manufacturing and exporting were buzzwords.

Now, the uncertain implications of a tariff whiplash are unnerving dealers and consumers in a country where a record 24 million vehicles were sold last year.

‘‘It is a nightmare to have the 25 percent additional duty,’’ said Wang Rongzhen, deputy general manager and an investor in Yan’an Jinchi Feike Auto Sales and Service Co. The Yan’an, Shaanxi-based dealership imports models such as Fiat Chrysler’s Jeep from the United States.

At Shanghai Aote Hung Car Sales, higher tariffs would just be another headache for sales manager Liu Yuanyuan, who says she’s struggling to shift stock as consumers anticipate the typical summer clearance discounts.

Her dealership imports models including those from Mercedes Benz, Buick, and Jaguar Land Rover.

Unless Trump backs down, on July 6 the United States will impose tariffs on $34 billion of Chinese imports, many of them parts used in products such as marine engines and power turbines.

China will impose countervailing levies the same day — including on US-manufactured cars. The auto tariffs will wipe out the July 1 reduction to 15 percent from 25 percent on all foreign car imports.