Just to clarify, I was thinking that opponent cars could have characters, but your own is just you, with no indication of gender or race.
Say for instance you start career mode and choose the same model car as another character, that's fine, you'll be customizing it to look different, anyway.
As for taunts, they definitely wouldn't happen every time, that would be non stop smack talk (ie. annoying as hell).
There would be an option to turn it off an on as well
That said, this wouldn't be a feature that we'd think about in the near future, more an added feature at the end if people seem to like it.
There are plenty more important things to do, I just wanted to get discussions going