I suspect this is a response to the rise of 3D printing.

If I have a 3D printer, and either a good 3D scanner or some measuring instruments and FreeCAD, I no longer need to go to Toyota/Ford/whoever to replace a broken tail light. I can just print my own. The same applies to any plastic part (up to the size of my 3D printer). I could even (perish the thought!) *improve* on the car's design.

http://www.thingiverse.com/search?q=car+parts&sa= finds 471 objects. Admittedly, most are to do with model cars, and there's a lot of non-car-part stuff. But there is a Chrysler PT Cruise fog light lens, Mazda Miata/MX5 window winders, Toyota engine bay clips, an MGB distributor shutter (whatever that is), a Kia Sportage sunshade clip, Honda Accord aircon knob, a Ferrari F1 steering wheel, a brake disc, a complete Maclaren F1 car body ( 4" X 8" X 2.5" admittedly, but no reason why you couldn't scale it up ), and quite a number of GPS/phone/tablet/cup holders of various kinds. I also noticed someone on TradeMe selling IIRC MkIV Zephyr interior light lenses.

And this.

This is the RIAA stupidity all over again... instead of embracing the new technology and saying "Thank God we no longer need to keep an inventory of spare parts... we could even reduce the price of new cars", the automobile industry chooses to legislatively protect their cash cow.