The efficiency argument is horseshit. U.S. autoworkers are more efficient than workers that live in countries that plants are moved to. The total cost of labor that goes into a vehicle is around $600-1000 usd so even if you had slave labor, it isn't like cars are all of a sudden going to be a lot cheaper. Most of the cost is just in the raw materials and parts. How much you shop around and negotiate probably makes a much bigger difference in what you pay than if the car was made in the U.S. or Mexico or South Korea. Even at that, just modest tariffs would be required to make it unattractive to move jobs oversees. These new autoplants that show up like the Toyota plant in Mississippi were built here largely due to small changes in the exchange rates are between currencies. If you forced foreign manufactures to compete under the same regulations: worker protections, environmental controls, ect. you would find U.S. manufacturing to be very competitive. Allowing corporations to do business here while carrying out the production in less regulated countries is method of further undermining very basic regulations and protection that were fought for and won in the 20th century. So much so, people are brainwashed into believing that the EPA, the minimum wage, unions, maternal leave, health insurance requirements are job killers. Free trade is only free when everyone is competing under the same rules.