Auckland Southern Motorway road crash: Driver dead after speeding car flips near Gillies Ave off-ramp

A couple who saw a fatal car crash unfold on an Auckland motorway last night have been left shaken and distressed after narrowly avoiding getting caught up in the crash.

The speeding SUV was weaving between traffic shortly before losing control and flipping near Gillies Ave on the Southern Motorway.

The SUV's driver was killed in the crash while the sole passenger was seriously injured, police confirmed this morning. The crash led to major motorway congestion.

A witness - who asked not to be named - said they were driving in the second lane from the left just after Gillies Ave when her husband saw a car speeding up in the rearview mirror, swerving between lanes.

He barely had time to say "Wow, they're going crazy" before the SUV hooned past.

"They were behind our car, then passed us and two other cars in front, before losing control," she said.

They saw sparks as the car crashed into the left-hand concrete barrier, flipping three times before landing on all four wheels, its roof smashed up. Another vehicle appeared to have collided with the SUV.

"Everything was very fast, we were very close, but fortunately avoided the crash," she said.

At least three cars stopped to help and they saw a person was approaching the car.

"We didn't see if people were injured - we were pretty much in shock because basically if we were in that lane it would have landed on us."

The pair kept driving and called the ambulance. "We were very shaken, so nervous, we wanted to move from the danger."

Inspector Grae Anderson, acting area commander for Auckland City Central, said the driver had died at the scene while a single passenger remained in a serious condition this morning.

The Serious Crash Unit was investigating, Anderson said.

Police were alerted to the crash in central Auckland about 8.10pm. Photo / Hayden Woodward

A crash on State Highway 1 near Epsom caused traffic to divert on the Southern Motorway. Photo / Haydenwoodward

Police said the southbound lanes were closed, with traffic needing to exit at Gillies Ave and detouring through to the Greenlane on-ramp.

The crash caused major motorway congestion, with reports of some motorists travelling just 100m in 40 minutes.

The motorway reopened overnight. Police are investigating the crash.