Thi Nguyen, 42, was ordered to serve a two-year corrections order with 150 hours of community work after she hit the 13-year-old with her car last November and fled the scene.

"You left (her) for dead. You ought to have known she was seriously injured," County Court Judge Gabriele Cannon told Nguyen on Friday.

"You did not stop after the collision in any meaningful way. You failed to do anything to help the person in need."

The Vietnamese-born woman was driving a black BMW along Bell Street at Coburg when the child weaved between lanes on November 5.

The girl was not wearing a helmet as she rode with friends into oncoming traffic.

Judge Cannon said she collided with the car's passenger side windscreen and "was thrown into the air before landing on the road".

A number of drivers went to the aid of the girl, who was placed in an induced coma with life-threatening internal injuries and a fractured rib.

A witness saw Nguyen get out of the car "to have a look" and then drive off, the court was told.

Judge Cannon said the girl had been seen riding erratically and it was "a matter of time before she was hit by a car".

She said Nguyen was blameless for the crash, but she should have stopped to help.

She added it "defies belief" Nguyen did not know someone had been seriously injured.

The judge said while Nguyen was of otherwise good character, she had shown a "gross lack of good judgment which was unlikely to happen again".

It took Nguyen four days to hand herself in to police after the crash and the judge accepted she was "afraid, panicked and concerned" about speaking to investigators sooner, due to her lack of English.

Nguyen had also wanted to speak to her solicitor before handing herself in.

The judge noted Nguyen felt "heartfelt remorse", prayed for the girl at her temple and hoped to apologise in person.

"I accept you are very sorry for your actions," the judge said.

Bicycle Network CEO Craig Richards said Nguyen will pay a "minor price" for a major error.

"Four weeks volunteering for leaving a young bike rider in a critical state on the road is not what the community expects and doesn't pass the pub test," he told AAP.

Nguyen, who pleaded guilty to failing to stop and render assistance after a motor vehicle accident, was disqualified from driving for four years.

Australian Associated Press