Thanks for the 3.5" vs 2.5" observation. I was thinking of the cheaper 3.5" drive, since space is not an issue. But I guess 2.5" is the way to go.

The intention is to permanently have the PC in the trunk, although I could have sockets and plugs for power, sound and VGA, which would allow for easy removal. I don't understand, what does docking not docking that have to do with drive life?