Free Software and Automobiles

Is there information on this?
If so, I would assume there is only something on a more high level for customizing something in a vehicle? Maybe something like customizing your radio? Just a guess of course.
Anyway, I am interested in knowing, now or later, about when it comes to low-level software running in a car that helps run the engine.
Is this or will this ever be possible for a driver/user to be able to look at and even customize the way the software runs the engine?
I could see something like this being a heavy political issue, for many in not wanting this.
I could have sworn that I heard something on the radio, back when VW was caught for the emissions scandal.