I would love to have something similar to a big flashcard that could pop up when needed. All you would need to do is press a button and the writing will appear on the relevant window, big and bold.
* When someone is right on your tail, and there are a million cars in front of you:
'Dude, I can't go any faster, the guy in front of me is blocked by the guy in front of him. Slow down, please mate.'
In the event the tail-gating driver ignores your request, you can press another button and release a massive blob of sludge that shoots out from your Bond-gadgeted car and lands on his bonnet.
* When someone overtakes you on a dangerous section of road, only for you to pull up next to him at the next traffic light:
'Well done bro, you made it here before us. You rock! Collect your prize at the next petrol station.'
If he glares at you, shoot out a puff of powder to fog up the view. Especially if he is a lot bigger.
* When the road is narrowing to a single lane, and the guy behind you is racing to get past:
'Slow down punk, this is not a Grand Prix'.
* When you hoot at, or gesticulate crazily at, someone who cuts in on you or jumps a red light, only for him to pull up next to you when you don't make it through the next set of traffic lights in time:
'Sorry man, that was my wife. She is attending anger management classes, just so you know!'
* At a fourway stop, when the traffic lights are out - South Africans are terrible at knowing whose turn is next:
'Your turn in the white car, red you're next, then back off everyone, I'm going!'
Let us know your suggestions.
Of course, some decorum would need to be applied, simply as a means for survival.
Try some of those moves on a taxi and you may need a bullet proof vehicle.