Personally, I wear a Cinci Bearcats hat whenever I'm not in the office, and my car has a stainless exhaust with a big tailpipe. I give half a lane every time, which is pretty often since my route home from work is all backroads between East Longmeadow, MA and Hartford, CT (popular bike route apparently).

Maybe my hatch-mount bike rack that I'm too lazy to ever remove really does offset the risk factors...