Buy car parts online from the major store brands

Most of the same car parts stores you pass every day also sell online. The advantage to buying online from these stores is that you can make returns to the store instead of return-shipping them. There's also something to be said for a vendor with a national consumer reputation, and someone to talk to face-to-face when you have questions about a part you bought online.

I recommend: Major auto parts stores with online outlets include NAPA, AutoZone and Pep Boys.

Buy auto parts from specialty online super-dealers

Online car parts retailers tend to position themselves much differently from the store-based retailers. They often claim that they carry a far greater range of automotive parts than the others -- they may stock that thermostat for a '67 Audi that AutoZone never heard of. Online sources also may have better prices, and they often carry the same part from a variety of manufacturers to give you more options -- often including OEM parts, aftermarket parts and used auto parts, so you can compare. Where a store-based retailer may offer three makes of spark plug to fit your vehicle, an online retailer may have ten, at a wide range of prices. On the flip side, many online parts stores are aimed at a higher proficiency level. Translation: They sometimes expect you to know what you want and what it does, and don't offer as much help as they might.

I recommend: Check out Auto Parts Warehouse, The Parts Center, Best Deal Car Parts, and Auto Parts Giant.

Locate hard-to-find used auto parts at online junk dealers

Sure, junkyards have always been the bargain basement of the car parts game. But now they are online, presented as "used auto parts" dealers. Online used parts stores are great for things that can be reliably rebuilt, such as alternators or water pumps, or for items of trim or fittings that are impossible to find elsewhere, like a dashboard for '99 Taurus. Although many used parts dealers warranty their wares, bear in mind -- it's cheap, but it's still used.

I recommend: There are individual used auto parts dealers, like EverDrive, which carries a complete used car parts selection and warranties all of its parts for three years from purchase. But more common are sites like Auto Part Search, a used auto parts site from which you can search the inventories of 250 junkyards -- sorry, "auto recyclers" -- for the part you want. Junk Yard Dog and Barely Used Auto Parts offer similar services.

Get OEM parts straight from your car's manufacturer

The dealer? Yes, the dealer. Why not? It's auto parts orthodoxy that a car part from the dealer is always more expensive and for no good reason. But knowing that they compete directly now with online retailers, many manufacturers' sites now offer competitive prices for their OEM auto parts. One caveat: They tend to carry only late-model parts; you're more likely to find that car part for your '84 Volvo from another online seller than from Volvo. Note too that you do not have to buy your OEM auto parts direct from the dealer; third-party online retailers sell both aftermarket auto parts and OEM auto parts.

I recommend: Here are some of the major auto manufacturers who sell their auto parts online: GM Parts Direct for General Motors cars; Ford parts; Mopar for Chrysler cars, Toyota parts, and Honda parts.

Style up with auto accessories - the car parts with class!

It's important to appreciate the distinction between "auto parts" and "auto accessories": If it came on the car when it was new, and now it needs replacing, it's a part. If it's unnecessary and you want to add it, it's an accessory. Parts include mufflers and air filters and windshields. Auto accessories include bike carriers, leopard-print steering wheel covers and mud flaps that say "back off!". The Internet is auto accessory heaven. You can find anything and everything you could ever imagine adding to your car -- and lots of stuff beyond your imagination.

I recommend: JC Whitney is the gold standard of auto accessories dealers, stocking everything from custom cargo liners to a car horn that moos like a cow (seriously). Other options include eAutoWorks.com and CarGear.com.