I thought it would be so perfect to listen to the SOTW CDs in the car as we drove :auto: to P.E. each week. The CDs were interesting to me but it didn't work for my kids (8, 6, 4). They do much better when I read it to them. I can tell when I have lost their attention and bring them back.
My friend borrowed them and she and her daughters (8, 9) have enjoyed them.
Since your kids already like to listen to stories in the car, I think it might work well for you.