If your auto insurance won't cover you for a U.S. rental, check to see if your credit card offers rental car coverage. Many American cards do, but I don't know if your's will. Your last option would be to purchase the collision damage waiver (or loss damage waiver) coverage from the rental car company. I assume it will be available for non-U.S. citizens. CDW/LDW usually is expensive, however, at around $15 per day.