When you’re asked for a deposit on a car—or any big-ticket item— use a credit card. If the seller can’t make good on the deal or misrepresents it and refuses to return your deposit, you can challenge the charge with your credit-card issuer. And if all goes well, you’ll get extra miles, cash back, or other card-related rewards based on the big charge. Just remember a credit card will protect you only if there’s a legal basis for breaking the contract with the seller.