HOUSTON --Nearly 30 million cars have been involved in accidents in the US in the past five years. A good many of those end up being totaled, even though a lot of their parts are still perfectly good. If you're willing to look for good, used parts, Consumer Reports says you can save a whole lot of money, but there are pitfalls. The workers at one auto salvage yard are taking apart cars that have been totaled, retrieving every usable part. Buying used car parts online can save you a bundle. "That total door might cost you $2,500, OK, if you bought all the components new. If you bought it used, it costs you maybe $1,000. So you're saving close to half," said salvage yard owner Anthony Martino. While people can come to the shop to look for used parts, the owner says many of his customers check out availability and prices online. Unless you're doing the repair yourself, Consumer Reports says before you shop, check whether your mechanic will do the work and what, if any, guarantee the shop will provide. "Be sure to check on whatever warranty the seller offers. They generally last between one and six months. If there is no warranty, check to see that at least you can return the part," said Jon Linkov with Consumer Reports. But Consumer Reports says there are certain parts you should never buy used. "Avoid buying anything that's related to safety or the functioning of the car. Those parts should only be bought new or rebuilt by a reputable supplier," Linkov said. Those car parts include: seat belts, air bags, brake parts, and electronic sensors that monitor system problems. "The safest things to buy used are parts like mirrors, bumpers, and alloy wheels. Even used parts like side-window glass and hoods can be safely installed," Linkov said. Once you find the part, ask the supplier if it meets Original Equipment Manufacturer, or OEM, specifications. That way, you know you are getting a part that the dealer or authorized mechanic would use. When you shop for replacement parts, you'll need the make, model, and year of your car, as well as the VIN number. It's also helpful if you have the number of the part.