[Johnny555]

Which is exactly how some people drive - an ex- used to make me car sick with the way she drove - rather than maintaing a constant speed, she'd speed up 'till she got too close to the car in front of her (dangerously close), then let off on the gas (or even tap the brakes) to slow down.

Annoying and led to no end of arguments "Why are you always criticizing my driving!?".

[wnissen]

With that style of driving, the minimum speed is also far more likely to drop to 0. And when one person is stopped, everyone behind them is stopped. Even for people who don't normally drive that way, add in a cell phone and that's exactly what starts to happen because they don't have enough remaining attention to avoid being "surprised" by a stopped car.