Mercedes faces similar issues with the vehicles it makes in Tuscaloosa, Alabama. Right now, a Mercedes M-Class utility vehicle made there carries a 10 percent European Union import tariff not levied on Mercedes sedans made in Rastatt, Germany.

Companies decide where to manufacture based on many factors including labor costs, taxes and currency risk. With a trade pact in place, though, tariffs and regulations might no longer need to be part of that calculation. Whether their business is cars, instant coffee or carbon steel, with corporations that work both sides of the Atlantic, the old-style notions of import-vs.-export and country of origin may no longer obtain.

European companies like Siemens, Nestlé and ThyssenKrupp have manufactured products in America for decades. But usually those were products destined for U.S. buyers. Once a free-trade pact is in place, it might make more sense for companies to export those products back to Europe.

The United States and the European Union are each other’s biggest trading partners, and a pact is seen as a cheap way for both sides to generate growth. But European automakers in particular could use a lift. Europe’s auto market has all but collapsed since the financial and economic crisis of 2007; last year, the number of vehicles sold in the Union was the lowest since the mid-1990s.

German automakers, which now sell more cars in the United States than they do in Germany, are particularly eager for a trade deal, which some optimists hope could be reached by the end of next year. A trade pact would no doubt intensify competition in the U.S. auto market, particularly at the premium end, by making it easier for BMW and Mercedes to export to the United States. But the benefits could also flow the other way.