The haunting clue police found in the car of the man accused of killing two in Sydney car crash.

-With AAP

A driver accused of killing a teenage girl and a heavily pregnant newlywed in a Sydney car crash had allegedly been drinking for about eight hours in the lead-up to the collision, a court has heard.

Police allege Richard Moananu was driving more than 45 km/h over the 60km/h speed limit when his Mazda 3 crossed to the wrong side of the road in Orchard Hills and collided with a Nissan Tiida in September.

Both the 17-year-old learner driver and 23-year-old passenger Katherine Hoang, who was heavily pregnant with twins, died at the scene.

Her unborn babies didn’t survive and her husband Bronko Hoang, who was also a passenger, was taken to hospital in a critical condition.

Following the crash, police found a letter from Moananu’s partner in his vehicle which questioned his priorities.

The letter read: “I’m at the age where being settled is what I need … you like to drink and gamble and be with your friends 80 per cent of the time.”

“I want you to think and ask yourself what is important to you.”

A wheelchair-bound Moananu, who suffered leg injuries in the crash, appeared in the NSW Supreme Court via video link for a bail application on Thursday.

The 29-year-old father-of-four is charged with numerous offences including manslaughter, aggravated dangerous driving occasioning grievous bodily harm and unlicensed driving.

Justice Natalie Adams, in refusing his bail application, said he had a “somewhat poor” driving history and there was an unacceptable risk he’d drive again.

She said the letter from Moananu’s partner suggested he’d already been “on notice” about his lifestyle.

Justice Adams said that on the evidence, Moananu had been drinking from 10.30am to 6.45pm that day and returned a .204 blood alcohol reading at the time of the collision.

“After getting that letter he drank all day,” Justice Adams said, according to the Daily Telegraph.

“He ignored it and now two people, two fetuses are all dead and there’s another person in hospital.”

A Daily Telegraph report from October reported Bronko Hoang screamed in agony when told his wife and unborn children had died.

His aunt Pham Crawford told the Telegraph that he felt guilty that he was the only survivor and that doctors had to sedate him to calm him down.

It’s also alleged traces of cannabis were found in his blood.

Moananu during his application said he was only getting one physiotherapy session a week at Long Bay Hospital and his mental health in custody was “not good” as he tended “to keep things inside”.

He and his family fought back tears as he told the court he did not know how to cope following the collision.

The court also heard Bronko Hoang remains in hospital about eight weeks after the crash.

He and his wife had only recently married after meeting and falling in love at the Western Sydney University Taekwondo club.