Fastest way to learn spanish in the car?

I teach high school and would like to learn Spanish to help Spanish speaking students. I have a 45 minute commute each way to work and would like to use that time. I looked up iPhone/ipad apps and was overwhelmed with how many there are and many seemed interactive (where I push icons etc.) and I can not do that on my phone. I am looking for something that has you speak Spanish and tells you if you got it wrong or not.
Is there such a think I can use in the car?