Just a little something that I think might add a little extra personality with the side effect of giving the players cues on what other cars are doing.
Basically, giving the drivers of the cars a voice, and having their lines correspond more or less to what they are doing.
So if say I get a certain car pissed at me and wanting a fight, instead of just silently going after me, their driver might shout something alluding to that. If I cripple an enemy car, both my driver and theirs might yell lines back and forth. If i start mowing down peds, or do something really crazy stunt, my driver or another one comments on it or laughs.
Bonus points for Screwie Louie and Max having special lines for each other pertaining to the issue of his legs, and any other characters that have feuds or whatever between them. Also cops chatting over CBs or megaphones while trying to ram you.
I think it'd be a good opportunity for humor and exploring the personalities of the psychos behind the wheel.
Also, i think being able to play as characters other than Max and Dieanna would be fun, for the above reasons.
Ideally something like this should probably be toggleable, as some people might not care for chatty drivers.