OEM BMW Parts

You have a few options. You can call the Parts department at your local BMW dealership, and speak to an impatient and testy rep. You can go to the counter and face that surly fellow in person. You can shop on the web with various places and hope that they have the part listed with the proper details. None of these options are really appealing, I know.

Instead, you should check out RealOEM.com. This is an awesome website that uploads the BMW ETK (parts catalogue) somehow, and it is exactly as if you had the same CD of parts that the BMW parts counter uses.

From there, just input the chassis, model, year, and you can navigate the parts categories (such as Vehicle Trim, Lighting, etc). You'll see diagrams and explanations, as well as the list price and part numbers. Then, when you call that surly fellow, you know what part you need to order and about what it should cost.

Even better, you can generally Google search the part number (without spaces) and find a number of great websites that offer it! Generally this is easier as they'll ship it to you, since your car may be out of commission if you're buying parts for it!

Aftermarket BMW Parts

If you're shopping for aftermarket BMW Parts and want to look them up, you won't have the same luck. There is no clear and organized listing of all the goodies available for your car, unfortunately. There are, however, some great websites both for shopping and for reading reviews of the parts. Such websites include forums like E46Fanatics, E90Post, and BImmerforums. I highly recommend you browse these forums if you're interested in any aftermarket part, because they serve as comprehensive sources for photos, reviews, and purchasing information. Make sure you use the search function, though - people hate when you "repost" a question that has already been visited 100 times!