So what you're saying is, the guy behind you, travelling at speed in another car, backed off frantically after he heard, from your car, a beep from above your head?
It is more likely that the beep was either unrelated or for some reason your rear PDC sounded. His braking is nothing to do with your car, its to do with the fact he slammed on the brakes too late.
How would a loud beep help in any event? A momentary bleep to allow you to kiss your ass goodbye? lol
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