Police allege a man who was preparing for a street drag race accidentally reversed into an innocent motorist's car, fled the scene, dumped the car and then fell 10 metres down a cliff.

Hornsby police say that on Sunday night a 33-year-old man was allegedly preparing for a street race at Leighton Place in Hornsby when he reversed his Holden Commodore into the front of another occupied vehicle.

Police have arrested a man for allegedly drag racing in Hornsby. Credit:Quentin Jones

He panicked, driving a short distance down the road that runs along an industrial complex, before dumping the car behind a factory and falling down a 10-metre cliff.

The 62-year-old driver of the other vehicle, a Honda Odyssey, was not injured in the crash. He called police immediately after the incident.