The ordeal began when Daniel Forsyth, 29, and Samantha Carpenter, 23, were cut off as they drove their Jeep near Fyshwick in November last year.

The driver of a Commodore in front of them made a "significant error" by pulling into their lane without checking blind spots.

It forced Forsyth and Carpenter's Jeep to swerve quickly to avoid a crash.

Enraged, they sped up and began screaming at the driver and his passenger, before forcing their Commodore from the road and wedging it in.

Carpenter got out and hit the windscreen before opening the door and punching the driver in the shoulder.

The driver said he apologised repeatedly and asked for forgiveness.

But Forsyth then approached, punching him in the right eye, and kicking him while he was still seated in the car.

He went to the car and came back with a knife still in its sheath, waving it in front of the driver's face. The driver remembers Forsyth saying words to the effect of: "This is not your country you bloody Indian, go back to your country and do it there."

The driver and passenger got out of the car, and Forsyth kicked the passenger and Carpenter grabbed and scratched the driver, saying: "you nearly killed my family."

The victim continued to apologise, and eventually Forsyth and Carpenter got back into the Jeep and began to drive away.

But they stopped when they saw the driver on the phone. The victim gave evidence that Forsyth said: "It's a bad idea to call the cops, if you call I'll come back and get you and your family."

The pair faced Chief Magistrate Lorraine Walker for judgment on Thursday.

Both had denied the allegations, and Forsyth said he'd never touched either of the victims or their car.

In evidence dismissed as "implausible" by the court, Forsyth claimed that the knife he waved in front of the victim's face was actually his mobile phone in a leather case.

He also claimed he did not see any injuries on the driver's face when he left the scene.

That was contradicted by independent witnesses who saw the injuries after stopping and turning around to help when they saw the scene unfolding.

It was also contradicted by photographic evidence of the man's face and by police who later pulled the Jeep over and found a hunting knife inside.

Forsyth was found guilty on Thursday of unlicensed driving, menacing driving, assault occasioning actual bodily harm, common assault, and possessing an offensive weapon with intent.

He was cleared of a threat to cause grievous bodily harm.

Carpenter was found guilty of two common assaults.

Both will be sentenced in late August.