The car computer is not usually EASILY ACCESSIBLE. If the car was in the shop, one COULD replace the entire computer BOX, but not the individual CPU chip.
HOWEVER, IF one could gain access to the interior of the car without setting off the alarms, all one has to do is drop in the proper CD into the CD player.
You're,,, mocking me, aren't you? :-)
But I do believe changes can be made to the program by plugging into the system. Just a thought.