...tariffs are 0% on vehicles shipped from Mexico...
Honda is building a full-sized assembly plant (200K units per year) as is Mazda; Nissan is adding a 3rd plant. Part of that is driven by the strength of the yen, at ¥81.3 per US$ on 17 November; the US is the biggest source of profits for the auto industry, so sourcing vehicles for the US market from a non-yen location is important. [The Euro is also strong, to which anyone who has traveled there on a dollar budget can attest. So while VW has operations in Mexico, here I focus on the Japan angle, because I'm teaching a course on the Japanese economy.]
But why Mexico? Logistics costs are high, because most vehicles will likely be exported and because the local supplier base is not as deep as in the US midwest (hence parts must be imported). So while quality is high and wages are competitive, it's not a priori a natural choice.