Motorists have been caught on camera stopping and reversing in the wrong lanes as they head towards the new WestConnex tunnel in Sydney, which opened early Saturday morning.

Key points: A woman has been filmed exiting her car on the middle of the road to ask a cameraman about the new tunnel

A woman has been filmed exiting her car on the middle of the road to ask a cameraman about the new tunnel Despite teething problems, ABC Radio Sydney listeners have called in to praise the new tunnel

Despite teething problems, ABC Radio Sydney listeners have called in to praise the new tunnel The NSW Premier says it could take months for driver numbers to pan out

The 5.5-kilometre twin tunnels on the M4 between Homebush and Haberfield opened to the public in the early hours of Saturday morning, with the first east-bound user escorted through about 2.30am.

Over the period of seven minutes, six vehicles stopped and reversed at the Haberfield entrance, unsure of which lane to use.

One woman even switched on the hazard lights of her car before she exited her vehicle to ask a cameraman for clarification.

Transport Management Centre spokesman Derek Peterson said for the most part, the tunnel was working well, but advised drivers to take extra care.

"Just be aware there are changed traffic conditions, so you will need to follow the new signs, the new lane markings," he said.

"Keep a safe distance from the car in front of you and in particular just be prepared to slow down or stop when exiting.

"This will be taking a bit of getting used to."

NSW Police escorted the first convoy of cars down the motorway early Saturday morning. ( ABC News )

Despite the teething problems, callers to ABC Radio Sydney gave the tunnel a thumbs up.

Eric called into the station after taking the east-bound tunnel.

"I stayed on the M4 from the Blue Mountains all the way through and it was just seamless," he told presenter Simon Marnie.

Travelling from the opposite direction, Blackheath man Michael said he even enjoyed the drive.

"I'd turn around and do it again, it was so much fun," he said.

"Except I've got no idea how much it cost me."

Drivers are being charged $4.27 for a one-way trip through the new tunnels, which bypasses 22 lights on Parramatta Road and saves up to 20 minutes of travel time.

NSW Premier Gladys Berejiklian and NSW Transport Minister Andrew Constance in the new WestConnex tunnels. ( AAP )

The real stress test for the tunnels, however, will be in a week's time when school holidays come to an end, increasing the number of cars travelling during the morning and afternoon peak periods.

NSW Premier Gladys Berejiklian said it would take weeks or even months for the number of drivers taking the tunnel to pan out.

Inner West Council mayor Darcy Byrne said he was facing Monday morning's peak with trepidation.