I totally understand and support what you are saying. I'm just not convinced the concept is sound enough to reach the goal you desire.
Would buying only American cars create more jobs here in the US and turn the economy around? Sure, if you can guarantee that the major US manufacturers would quit outsourcing jobs to places outside our borders for lower costs and higher profits. Then get the unions to follow along and not line their pockets on the backs of their members or hold out on an agreement until it breaks the company. The feds and states have a role in this also.