Hi Kristen:
We love Raffi CDs in the car for happy hearts, and in terms of educational content, these are some great podcasts for short attention spans and long car rides!:
https://itunes.apple.com/ca/podcast/sesame-street-podcast/id264537349
https://itunes.apple.com/ca/podcast/little-stories-for-tiny-people-anytime-bedtime-stories/id1039511252
https://itunes.apple.com/ca/podcast/story-time-childrens-bedtime-stories-for-kids-storytime/id991313597