For my first "action cam", I have decided on the Mobius Mini with wide angle lens. This seems to be a popular choice among the R/C guys due to the small size and light weight. In addition, the videos I've seen taken from vehicles looks very good to me. These are priced under $100 (if you look in the right places). The basic features are: HD video up to 1080P30, 116 degree lens, Micro SD card slot, and LiPo battery. If you're interested in checking this out, here is a good YouTube on it:

https://www.youtube.com/watch?v=7wmIyD1fM4M

I haven't received this yet but when I do, in another week or so, I'll post an update. Finally, I definitely could have spent more on an action camera but just to see whether or not this is something I will really use, this seemed like a good one to start with.