travel time, leisure converted to work?

I am obsessed with the idea of effective use of time and making maximum productivity out of the time one has. Lately I have thought that I am effectively "wasting" the time I spend driving. Sure, I kinda can't get around the fact that I need to drive to get places and that this activity can take quite a lot of time (for reference see post regarding what I do with my life, i.e. how I spend my time). I spend hours driving and so far I have used that time to.... drive for one and to listen to music. What a waste of valuable brain time! I could be recording a novel! Or recording anything awesome! Or studying (somehow)! Or improving myself! I have decided to try to use this time more effectively (multi-tasking in effect) by doing more productive things while driving (nothing dangerous). I started an audio book (The Giver). I might try to learn Chinese or some other language while driving. If you have any ideas for activities, let me know.