Sometimes a manufacturer makes a design or production mistake on a motor vehicle. A service bulletin notifies the dealer of the problem and how to resolve it. Because these free repairs are not publicized, they are called "secret warranties." The National Highway Traffic Safety Administration maintains a database of service bulletins filed by manufacturers.

If you have a problem with a vehicle that is a safety hazard, check whether the manufacturer has recalled your vehicle. Click on Recalls or call NHTSA at 1-800-424-9393.Hazards that aren't listed should be reported to your dealer, the manufacturer of the vehicle, and NHTSA. If a safety-related defect exists, the maker must fix it at no cost to you-even if your warranty has expired.

If you have a vehicle with a unique problem that just never seems to get fixed, you may have a lemon. Some states have laws concerning lemons that require a refund or replacement if a problem is not fixed within a reasonable number of tries or if you haven't been able to use your vehicle for a certain number of days. Contact your local consumer protection office to learn whether you have such protections and what steps you must take to solve your problem. If you believe your car is a lemon:

• Give the dealer a list of the problems every time you bring it in for repairs.
• Get and keep copies of the repair orders listing the problems, the work done, and the dates the car was in the shop.
• Contact the manufacturer, as well as the dealer, to report the problem. Check your owner's manual or the directory for the auto manufacturers.
• Help other consumers avoid purchasing your lemon by registering it at www.safetyforum.com.

The Center for Auto Safety gathers information and complaints concerning safety defects, recalls, service bulletins and state lemon laws.