Are you implying that cars have chips running some form of Linux? If so, I think they're late on complying with the license. I know at least my car's manual doesn't have an offer for source code, nor did it include any digital medium.
The Automobile manufacturers are responsible for that when they build the car. Linux (in some form or another) as an embedded OS is in hundreds if not thousands of devices from you car to your MP3. My brother owns a Toyota Prius and has installed an RPM on it that allows him to access the system through an additional menu option on the monitor. The additional menu will give him more information on the system as well as allow him to run the car on all electric or all gas. It's a Linux OS that runs that car. Toyota takes care of your licensing, source code and digital medium. The ECU's that you hear about in cars are running a form of Linux. Sit and think about how many computers you REALLY have in your house and realize that 80-85% of them are running a version of Linux.