There's a certain coolness in customizing your own car, as opposed to just strolling into a dealership and picking one out. It's kind of like ordering at a sandwich shop: you’re presented with a smorgasbord of options (short alpha-numeric codes) to pick and choose from. The end result can be sublime, perfectly tailored to your tastes -- or, so hideously awful, the manufacturer adds a label that essentially says "look, this wasn’t our idea."
Every now and then, there’s a secret Easter egg on the ordering form -- something unbelievably cool, like an unadvertised option (see: the now-legendary COPO Camaro) or a specific option combo that'll trigger additional equipment you wouldn't get otherwise. Even cooler? Sometimes you can buy these cars for super cheap -- if you get a seller who doesn’t realize what they’ve got.
I discovered one of these hidden options when I ordered my car last year: a BMW 228i with both the M Sport Package (ZMM) and the Track Handling Package (ZTR). As a result, it came with an extra radiator -- a happy surprise, since it means I can take longer stints on a race track in the 100-degree Texas summer without overheating my car.