Your insurance company promises to return your vehicle to its pre-accident condition after you're involved in a crash. Unfortunately, the definition of "pre-accident condition" is hazy at best, and the use of original equipment manufacturer (OEM) parts at repair time could develop into a tug of war.

OEM parts are manufactured by the maker of your vehicle. Non-OEM parts, often called aftermarket or generic parts, are made by third-party vendors. Many insurance companies recommend non-OEM parts for the repair of damaged vehicles to keep insurance costs down. The industry sees non-OEM parts as quality replacements that are guaranteed and a perfectly reasonable alternative to OEM parts, and less expensive.

Insurance policy coverage requires repairs that use "certified" parts, parts of  "like kind and quality," or "functionally equivalent" parts. These are commonly called aftermarket crash parts. These aftermarket parts usually cost less than genuine OEM parts.

Many consumers aren't aware that their car insurance coverage may allow use of aftermarket parts. One of the easiest ways for for you to ensure you get the highest quality parts is to choose an insurance policy that assures use of OEM parts. Read your policy carefully and ask your agent before you have a claim.

For example, Chubb Personal Insurance auto coverage pays for OEM parts and GMAC Insurance has a "SmartParts Promise" guarantee of OEM parts in collision repairs.

State Farm issues repair estimates using only OEM parts for exterior crash parts, although the company may prescribe aftermarket parts for non-crash components, such as batteries and headlights. State Farm sometimes also recommends recycled crash parts, mainly for older vehicles, when it believes a recycled part will restore the vehicle to its pre-loss condition.

You are certainly entitled to demand OEM parts after you crash your car, but your insurance company might not pay 100 percent of the repair bill if you do.

Others insurers may offer an option to assure use of OEM parts for an additional premium.

For example, Progressive Casualty Insurance Co. generally recommends that non-safety related parts, such as fenders, be replaced with non-OEM parts so the company can save money.

"We have an obligation to keep the cost of auto insurance down for all of our customers, whether or not they've been involved in an accident. If we paid for higher-cost OEM parts when non-OEM parts would allow us to return the vehicle to its pre-accident condition, we would overpay claims, which would result in higher costs to our customers," says a Progressive spokesperson.

Progressive policyholders can request that OEM parts be used for repairs, but they will have to pay the cost difference between the OEM part and aftermarket part if the Progressive claim representative believes that an aftermarket part is appropriate.

A litigious issue

Past and current class action lawsuits may make insurers more cautious in recommending aftermarket parts.

There is currently a class action suit pending against Progressive about the company's practice of specifying aftermarket replacement parts in the repair of policyholders' vehicles. The plaintiffs allege that these aftermarket parts are inferior and don't bring a car back to its pre-loss condition. The case is still pending.

Farmers recently settled a class action lawsuit (Lebrilla vs. Farmers) that alleges non-OEM parts don't meet the quality standards required by Farmers' auto policies. The settlement encompasses accident-repair claims made between June 15, 1996, and Nov. 1, 2006.

In settling the case, Farmers denied any wrongdoing and the company states, "Farmers has had internal guidelines concerning the use of certain non-OEM parts such as those certified by the Certified Automobile Parts Association ('CAPA'). When Farmers specifies these parts, it does so to keep repair costs down. Through this lawsuit, it has now been brought to Farmers’ attention that a number of the parts it specified did not meet those guidelines. The Court has made no determination of the quality of the parts involved in this case." Farmers agreed to pay $17 million in costs and attorney fees to the lawyers for the class.

Farmers policyholders who had claims affected by the lawsuit, which include customers of Farmers Insurance Exchange, Mid-Century Insurance Co., and other affiliates, had to file claim forms to receive $40 for each eligible hood and $20 if their crash repair required other exterior parts, such as fenders, quarter panels, tail gates and trunk lids.

The Insurance Institute for Highway Safety (IIHS), which conducts crash tests, maintains that non-OEM parts do not degrade the safety of a vehicle involved in a crash. The IIHS refers to crash repair parts as "cosmetic parts." According to IIHS, the source of "cosmetic parts" is "irrelevant to safety because the cosmetic parts themselves serve no safety function. They merely cover a car like skin," with the exception of hoods, which must buckle properly during impact. And the IIHS says that "there is no evidence that hoods from aftermarket suppliers fail to perform as well as original-equipment hoods."

Really cheaper?

Aftermarket parts are certainly cheaper, but why? In a friend-of-the-court brief, Public Citizen, a consumer-watchdog group founded by Ralph Nader, says, "Non-OEM parts can be sold at reduced rates because their manufacturers do not bear the cost of research, development, advertising, or special packaging . . . [and thus] the cost-savings made through the use of non-OEM parts runs into the hundreds of millions of dollars" for large insurance companies.

Some believe there is other reason to beware. For example, testing conducted on behalf of GM, a maker of OEM parts, shows there can be big differences between aftermarket parts and genuine OEM parts.

In tests on a Chevrolet Cavalier bumper system using OEM and non-OEM parts, GM concluded that "non-OEM parts may not satisfy the consumer. And, when all the costs are included, cheaper non-OEM parts may not save money in the long run." In a 5 m.p.h. impact test, the non-OEM bumper suffered greater damage and cost $1,500 more to repair.

Insurers are getting more savvy about costs associated with OEM parts. According to CRASH Network, a news source for the collision-repair industry, State Farm has negotiated deals with original equipment manufacturers that will give State Farm a 3 percent cost break off MSRP when it buys OEM parts for use in its direct-repair "Select Service" shops.

Pressure to accept aftermarket parts

Consumer Reports surveyed subscribers who filed auto-damage claims between January 2001 and Spring 2004 and found that 6 percent reported being pressured by their insurers to use non-OEM crash parts such as fenders, doors and bumpers. Of those who felt pressured to take the aftermarket parts, only 37 percent were very satisfied with the quality of repair vs. 72 percent of those who didn't feel pressured.

According to Consumer Reports, these four insurers were judged more likely than average to pressure claimants to accept aftermarket parts: American Family Mutual (11 percent), Nationwide Mutual Fire (11 percent), Nationwide Mutual Insurance Co. (12 percent), and Commerce Insurance Co. (14 percent).

Look before you lease

If you lease your vehicle, your lease company requires the vehicle to be in the same condition when you turn it in as when you began the lease. Some auto leasing companies forbid their lessees to add any parts that would reduce the vehicle's value. Under some lease contracts, you can't replace any parts without the leasor's permission. This means that if you're involved in an accident and have to make repairs, you'll likely have to use OEM parts. The question is, will your insurance company pay the full OEM amount?

If your insurer feels it can repair your leased vehicle to its pre-accident condition with non-OEM parts, you're probably going to be in a bind. Your lease might say explicitly that you have to use OEM parts at repair time, or it might imply that OEM parts must be used. If you choose OEM parts, you may need to come up with the difference between an aftermarket part estimate and the OEM estimate.

Choosing not to use OEM parts might cost you a part of your security deposit at the end of the lease or you might be charged a disposition fee (typically between $200 and $500) when your lease runs out.

Resale value

Consider whether you're going to trade-in or sell your vehicle before making a decision on using OEM parts. "If you're buying a Mercedes, you're buying it, in part, for the craftsmanship," says Cristoph Ritterson, vice president of Chubb. "Who's going to want to buy a Mercedes with non-Mercedes parts?" Dealers routinely check the crash history of a vehicle to see what kinds of parts were used in its repair, according to Ritterson. Your resale or trade-in value might be hurt if non-OEM parts are used.

By the same token, you don't want to buy a patchwork vehicle from a dealer, so the onus is on you to check the vehicle's crash history if you're suspicious of its condition. Web sites like Carfax.com and eztitlesearch.com will run the vehicle history. Although you won't be able to see whether or not the vehicle was repaired with OEM parts, you will be able to see if the vehicle was damaged in a major accident in the past.

Know, too, that you have the right to ask for OEM parts whenever you've been involved in a crash. Most auto policies say the insurance company will return your crashed vehicle to its pre-accident state with parts of "like kind and quality." Policies generally don't exclude the use of OEM parts (although your insurance company might not repair vehicles with OEM parts as standard practice), so don't be shy about insisting. In addition, some states do not require insurers to disclose to policyholders their use of non-OEM parts (see sidebar). It's important to know that in these states, you have to ask.