I believe the car is holding back SO MUCH stuff that folks using a smartphone is their only recourse.
The PC industry was based around a "screwup" on IBM's part - it opened the PC architecture. They tried to correct it (remember the PS/2 and OS/2 and the proprietary microchannel architecture?)
The rise of windows was based on this open architecture. Microsoft pushed to have PCs become a commodity so windows sales would be strong. (Read up on substitutes and complements - if peanut butter prices go down, jelly sales will rise).
I believe if the car manufacturers opened up their cars like the IBM PC and it's bus, put in *simple* plug-in slots or something similar for computer hardware, all kinds of crazy and useful stuff would come to your car. Imagine if you (not an installer) could change or add to your car stereo like plugging in a graphics card or sound card? (probably would work better like a rack - think smaller 19" rack mounting for audio equipment, except with standard interfaces in the back)