Sitting in an auto dealership haggling with a salesperson over the price of a new car may be more fun than a root canal, but probably not much. You can get loads of advice on how to negotiate at online sites like Edmunds (www.edmunds.com). Buy toward the end of the month, when sales staffs are eager to fill quotas, and go when the weather is lousy and any customer looks like a live sales opportunity to dealership personnel. Many consumer advisors suggest, however, that just one question can be the most effective bargaining tool. When the salesperson arrives at the seemingly final price, ask if that's the best they can do. That simple question can save you serious money.