Whats up with their faces? They look kinda mutated.

they are not mutated. gearheads are the most intelligent clan in wasteland. they have technology which they don't want to share with other clans. there are 6 different clans in the game. check this out.

http://en.wikipedia.org/wiki/Rage_(video_game)

I know they're inelligent, I just thought maybe it could have something to do with them mentioning chernobyl. :shrug:
Either that or their armor has some...negative effects.