At first I couldn't figure out how this happened. But when I Googled "Garden City" + "ghost car," a helpful discussion on the JREF forum cleared it up.
First, watch the video and see if you can guess the answer. I'll wait right here.
.... (hums, taps his feet, checks his watch) ...
Okay, so how was it done?
There's actually only a short section of fence. The speeding car has already passed the fence when the camera swings back to it. The taillights are visible from behind the fence, but because they are bright and the fence is dark, they give the momentary impression of being in front.
Thus it looks as if the car is miraculously passing through the fence, when in reality it zipped around the obstacle before the camera reacquired the car.
HT: Ace of Spades.