A TEENAGE thug ambushed an autistic stranger's car and terrorised him with death threats as he smashed the vehicle up.

Robbie Hagen stepped in front of the Citroen C3 and forced his victim to stop before jumping on the bonnet and booting the windscreen until it shattered and caved in.

Hagen, 18, has now been jailed for the unprovoked daylight attack in Port Glasgow.

The lout got into the car beside its petrified 20-year-old driver after holding it up on Clune Brae and demanded to be taken to the town centre.

He was charged with assaulting the young man by repeatedly punching him on the head but his not guilty plea to this was accepted following negotiation between the Crown and defence.

Prosecutor David Glancy told Greenock Sheriff Court: "This was a totally unprovoked attack on an innocent member of the public going about his daily business, and who has a diagnosis of autism.

"The incident caused him extreme distress."

Explaining the circumstances, fiscal depute Mr Glancy said: "The complainer refused to drive on and the accused got out and went to a nearby garden, bringing himself to the attention of a woman.

"The young man within the vehicle looked terrified and was scared to open the door.

"The woman told the accused to stay put and she got into the car to find out what had happened.

"The accused then approached the vehicle and he began to punch and kick at the driver's door and window.

"This assault caused the door handle to detach and it fell off.

"The accused then jumped on the bonnet and kicked the windscreen until it smashed."

Mr Glancy added: "He was shouting at the driver to get out and that he was going to kill and stab them."

Hagen, whom the court heard has a 'chaotic lifestyle', committed the offences at around 2.20pm on January 22.

When he was cautioned and charged he told police: "That's a lie."

Hagen's lawyer, David Tod, said: "I wholly accept that this was distressing for the people involved.

"The social work department believes that Mr Hagen can be worked with."

Sheriff Thomas Ward told Hagen: "This was a totally unprovoked attack.

"This is not the wild west, but that's how you're behaving.

"In the circumstances I consider there is no other appropriate way of dealing with you other than by way of a period of detention."

Hagen was sentenced to 130 days, backdated to January 23 when he was first remanded in custody.