Finally it does work on iPhone 5.

I reviewed earlier that it didnt work on iPhone 5, but it does. It just takes a loooooong time to extract a map. It said it was done downloading but no map. About 20 minutes later I was in another app and navigon pops up saying extracting map, so you may have to wait a bit but it will work.

Mid Missouri about NAVIGON U.S. Central, v2.2