U.S. auto stocks are getting hit Tuesday, Oct. 2. after some of the major automakers reported disappointing sales numbers. 

General Motors Company (GM) - Get Report fell more than 2% Tuesday afternoon, Ford Motor Company (F) - Get Report shares fell as much as 1% and Fiat-Chrysler Automobiles N.V. (FCAU) - Get Report shares also fell as much as 1%.  

GM reported an 11% sales decline from the third-quarter of 2017. The car maker sold 694,638 cars in this year's third-quarter. Ford reported U.S. sales for the month of September fell 11.2% from the same month last year to 197,404 vehicles. Fiat Chrysler posted higher September sales in the U.S., up 15% year over year, boosted by strong sales of Jeep and Dodge branded products.

White House trade officials reached an agreement with Canada over the weekend to revamp NAFTA. Increased costs as a result of tariffs on both metals and whole vehicles have put pressure on automakers' gross margins.

But while many may have thought the NAFTA rewrite, called the USMCA and still subject to congressional approval, will be a boost for auto companies going forward, the agreement, may pose problems 

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"At first blush, the USMCA deal appears to be saving the automotive industry some major headaches, but we're not quite out of the woods yet," Ivan Drury, Senior Manager of Industry Analysis at Edmunds told TheStreet.

While it does seem that the U.S. is getting rid of the 25% tariff on imported cars, it's now requiring U.S. car makers to  buy autoparts only from the North America region, rather than from China, where parts are cheaper. "The elimination of a 25% tariff on imported vehicles is a huge win, but the new regional value content requirements mean that automakers will not able to source parts as freely, so there will be added costs associated with vehicle manufacturing," Drury said. 

"These parts are being sourced from foreign places because they are cheaper there," Drurty said. "If you could locally source parts stateside [within the country], they'd already be doing that." 

It's also possible that some of these local suppliers will have more pricing power, albeit marginal pricing power. "To some degree, certainly [there is pricing power]," Drury said, "but not full throttle."

Car makers may try to pass along any added costs to the consumer, but that may prove difficult in a rising interest rate environment. "The only logical end game is that they're going to have to spend more money, and they will have to pass on this additional [cost] component to the consumer," Drury said. However, in the wake of the latest rate increase by the Fed, "I have been hearing that there are people that aren't qualifying for car loans," Drury said. 

GM is down almost 20% this year. Ford is down more than 25% this year. Fiat-Chrysler is about even with where it started the year. 

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