It's a map thing for me.
Driving: Gephy, Death Island, Infinity, Timberland, Sidewinder
Gunning (either gun works for me): Blood Gulch, Danger Canyon, Ice Fields
But I will go into any seat available, most of the time I automatically go for the driver seat, whether there are people around or not. but it doesnt matter what seat I'm in, because for some really odd reason, it doesn't matter what seat I'm in, where the rocket hits, where the nade gets stuck, where the chain gun is shooting...I'm ALWAYS the FIRST one to DIE