I sit in the back and hope they don't want to talk, because I won't be rude and not talk back, but I don't want to tell some strange dude (because I've only once ever had a lady driver) about my plans or where I'm from or too many details about myself. it's not an "I don't talk to the help" thing, because if it wasn't personal questions I wouldn't care, but I don't need some rando knowing where I'm staying or if I'm alone or how long I'm in town or whatever, and I'm already taking a risk getting in their car alone and trusting they'll take me where I say.