The breadth of an auto tariff would initially dictate what segments of car sales are affected. For instance, if Trump followed through on his threat specifically against the EU, it would largely affect luxury brands that ship from Europe, such as Mercedes-Benz and Audi, Drury said.
Exactly how much prices would rise would depend on whether automakers pass on the full increase to U.S. buyers.
For illustration purposes: If a full 20 percent tariff against EU imports were passed on to consumers, the starting price of a 2018 Mercedes SL Roadster would jump by $17,640 to $105,840 from its current $88,200.
Meanwhile, if the tariff were imposed on all imports regardless of country of origin — which could come about from the Commerce Department evaluation — a broader swath of the market would be affected.
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LMC Automative's Schuster estimates about 8 million imported cars would be hit in that scenario. About 17.5 million cars were sold in the United States last year.
The average price of a new car is about $34,600, according to Edmunds data. Again for illustration purposes: If an import cost that amount, a 20 percent increase would translate into an extra $6,920, for a total of $41,520.
“If you add that kind of increase, you’d be looking at consumers replacing a substantial number of those vehicle purchases with used cars, or they’ll delay their purchase,” Schuster said.
Some foreign automakers manufacture various brands in the United States. Those cars would not be subject to tariffs.