When a major purchase is made, the manufacturer or seller makes an important promise to stand behind the product, known as a warranty. Federal law requires that warranties be made available for the owner to read, prior to purchase. This also includes shopping by catalog and the Internet.

When deciding which car to buy, it is advisable to check the auto warranty that comes with the vehicle. After all, not every new car warranty is created equally. The purpose of a warranty is to protect an owner from any major expense, in case of mechanical failure or breakdown. A basic warranty covers major components like the engine, transmission or transaxle and belt drive. The best warranties also cover antilock brakes, heating and air-conditioning systems, air bags, overheating and most of the accessory and computer systems.

A new car warranty applies to new vehicles and is valid even with a change in owner. A full manufacturer's warranty provides all services necessary, free of charge to the owner. It also allows for diagnosis of all covered systems, and removal and reinstallation of all covered parts within a system. Many dealers provide a loaner car during both scheduled and emergency service procedures. Legislation in most states allows the consumer to choose, either a replacement or a refund, if the vehicle can't be repaired after a reasonable number of attempts.

Most new car warranties cover all the non-wear items on the car up for three years or 36,000 miles. Others cover repairs for longer periods, like10 years or 100,000 miles. The strength of the coverage that is included helps a buyer decide whether to purchase an extended auto warranty, over and above the existing company provided warranty.

New cars driven out of showrooms are fully covered by manufacturer