Millions of lines is an exaggeration... You can't add up the code for the ABS to the code for engine control, to the car navigation system. Those systems may s

Millions of lines is an exaggeration... You can't add up the code for the ABS to the code for engine control, to the car navigation system. Those systems may share information, through limited signals or simple data busses, but they are separate, not a big code blob like a PC or a server.