WASHINGTON/MEXICO CITY, May 29 (Reuters) - The Trump administration wants to increase the level of regional content in North American-built vehicles to 82% to qualify for preferential treatment under the U.S.-Mexico-Canada Agreement on trade, with 50% of that value produced in the United States, four people familiar with the U.S. negotiating position said.

The proposal, unveiled during this week's U.S.-Mexico negotiations over revisions to the six-year-old USMCA in Mexico City, has no provision for requiring any content from Canada, which is not represented at the talks, the sources said.

The shift, if accepted, would be a major break from the current USMCA, which requires that 40% of the "core parts" value of North American passenger vehicle passenger cars be produced in high-wage jurisdictions, effectively the U.S. or Canada. That threshold is 45% for pickup trucks. Overall vehicles must have 75% North American content to qualify for preferential treatment under USMCA.