The act of mashing the gas pedal as soon as you see the left turn arrow turn green in your periferal vision, even though you are in the straight lane, causing a moment of embarassment as no fewer than 8 people think less of you as a man
little timmy started to make his left turn, when a man almost ran into him head on after a premature acceleration
When the person behind you in traffic changes lanes and accelerates to pass only to find that there is not enough room and they have to get back in line.
Driver: Did you see that guy try to pass me? He had to slow down and get back in line.
Passenger: Yeah, that was a case of premature acceleration.
When a automobile begins to accelerate before it is prudent. Most often witnessed at intersections that are controlled by traffic lights when a driver incorrectly assumes that it is his turn to go next.
Driver: Look at that guy raring to go. I'll bet he doesn't know that it's my turn to go next.
<Car in question moves about a foot and then stops abruptly as he realizes his light did not change green>
Passenger: How embarrassing; a classic case of premature acceleration.