The NAFTA replacement launches under a cloud of disputes, with the U.S. considering new tariffs on Canadian aluminum and growing concerns over Mexico's ability to meet new labor standards in the deal.

Automakers would have until the end of 2020 to fully certify that production plans comply with the new trade pact's rules and U.S. Customs and Border Protection will apply an "informed compliance period" for the first six months of 2021.

Modestly higher prices for cars and trucks are a possibility, given the upheaval likely from the agreement's new rules of origin and labour provisions.

The Trump administration is considering re-imposing tariffs on aluminum imports from Canada and an announcement could come by the end of the week, according to people familiar with the matter. And just the possibility of the tariffs has drawn the ire and criticism of the Canadian Automotive Parts Manufacturers’ Association.