Police are hunting a group of men accused of using a crowbar in a "cowardly" high-speed road rage attack in Sydney's south.

CCTV footage from inside the M5 tunnel in Arncliffe shows a black BMW X5 ramming a Holden Astra at high speed in October last year.

The attack forced the Astra to crash into the tunnel walls, narrowly missing several other cars.

Police said one of the men in the BMW had earlier thrown a crowbar at the Astra while it was stopped at traffic lights on Seventh Avenue in Mascot.

They said the 18-year-old driver of the Astra, who had two teenage passengers onboard, tried to drive away before being rammed and threatened by three of the men from the BMW armed with a crowbar, a wrench and other weapons.

Police allege the men inside the BMW then chased the Astra at high speed into the M5 eastbound where it crashed, before leaving the scene.

The Astra is seen blocking both lanes after crashing into the tunnel walls. ( ABC News )

Chief Inspector Phil Brooks said it was a serious case of road rage which could have had catastrophic consequences.

"This is a very busy part of Sydney, there would have been significant traffic in and around the airport precinct," he said.

"This is a clear case of road rage.

"The four young men in this black BMW X5 have all been very cowardly in their behaviour, spooking these three young men in the Holden Astra.

"Given the current state of the road toll — 392 last year, 29 so far this year — it's this sort of risky driving that is costing lives on our roads."

The moment a black BMW rammed a Holden Astra, causing it to smash into the M5 tunnel wall. ( Supplied: NSW Police )

The man alleged to have thrown the crowbar at the Astra is described as being of Caucasian appearance, about 20 years old, with blonde/brown hair and wearing a black jumper and black shorts.

"We're certainly appealing for anyone who's got dashcam footage of this event unfolding on Sunday the 15th October at 8.45pm," Chief Inspector Brooks said.

"We're also appealing for businesses where this black BMW has pulled up, petrol stations or food outlets."

Chief Inspector Brooks urged anyone with information to contact Crime Stoppers.