I found this section interesting:
"VW’s luxury unit, Audi, considered the U.S. when it was deciding where to build the hot-selling Q5 sport utility in North America, says Bernd Martens, the company’s board member for procurement. Mexico had a $500-per-car labor cost advantage, but that was offset by higher transportation costs. The clincher was Mexico’s trade policy. Specifically, the U.S. lacks trade agreements with Japan, the European Union and Brazil. Added tariffs mean a car exported from Tennessee to Brazil costs 55% more than one exported from Mexico."
Even though there is a labor cost savings it is eaten up by the logistics cost. However, they get to export their cars to other countries with less tariff cost.