Irrespective of where I am, if there's an option and I'm alone, I ride up front. On top of things like car sickness, safety, feeling chatty, making sure we're heading in the right direction (one mini-cab driver taking me from my flat in north London to LHR didn't even know the way) etc. I also feel slightly awkward sitting in the back like the cabbie is a chauffeur. If I'm with one other person, I sit in the back and more than one I try to call shotgun and sit up front.

Of course I've had a few cab drivers who are a little bit TOO chatty and I wish I had sat in the back (another LHR run I had some chap tell me how he would often trade cab fares for sexual favours with drunk girls and then proceeded to give me details).