"Domestic content data
The U.S. federal government uses several approaches to determine the
domestic content of vehicles sold in the United States. All of them
define "domestic" as a geographic concept, rather than strictly by
nation of ownership.
For regulating fuel-efficiency, the U.S. Environmental Protection
Agency considers a vehicle to be domestic if at least 75% of its
content is produced in North America, including Canada and Mexico.
For setting import tariffs, the U.S. Department of Treasury, Customs
Service considers a vehicle to be domestic if it has at least 50% U.S.
or Canadian content.
For informing consumers, the American Automobile Labeling Act of 1992
(AAIA) considers a vehicle to be domestic if at least 85% of its parts
originate in the U.S. or Canada; a part is counted as domestic if at
least 70% of its content comes from the U.S. or Canada."