As I understand it, you would not lose the tax you pay to California. You pay it up front when you pick up the vehicle, then they will refund all of it when you register it in your home state, no matter what your state tax happens to be. I bought a new car in CA and I live in Nevada. That was the way it was explained to me a few years ago. The drawback was that you had to wait a bit for your refund. oclv