Representatives of the big three U.S. automakers, including the CEOs of GM (Mary Barra) and Fiat Chrysler (Sergio Marchionne), met with Vice President Pence and USTR Lighthizer to outline concerns about proposed NAFTA rules-of-origin. These include disruptions to supply chains that may increases costs, and possibly prices for consumers.

The big three automakers currently import significant quantities of parts to Mexico for assembly into final vehicles. That includes Europe for Ford (59% of the total in the past year), Japan for Fiat-Chrysler (16%) and China for General Motors (15%...