Detroit's major car manufacturers are reportedly preparing to alert the Trump administration that proposed revisions to the North American trade agreement could cost them billions of dollars and weaken their ability to compete against foreign rivals.

These automakers are still absorbing the financial impact of a series of tariffs imposed by the government last year, including duties on steel, aluminum, auto parts, and vehicles imported from Mexico and Canada. They also point out that competitors from Japan, South Korea, and Europe face a lighter tariff burden.

Now, industry executives are concerned that a proposal put forward by Washington ahead of next month's trade talks with Mexican officials could further elevate costs. One of the most contentious issues, as reported by media in May, is the requirement that vehicles must contain at least 50% U.S.-made parts to qualify for lower tariffs.

According to estimates from two automakers, this stipulation, combined with a suggested increase in the overall regional content requirement for vehicles in North America from the current 75%, would add at least $2 billion in annual costs for each Detroit-based company. These expenses would come on top of the costs automakers have already incurred from existing tariffs since last year.

The Office of the U.S. Trade Representative (USTR) did not respond to a request for comment. Government officials have stated that the tariff measures are designed to encourage more investment in U.S. factories and create jobs.