Malaysian police have stepped up a manhunt to locate four suspects involved in the brazen murder of a businessman at a petrol station in Johor Baru on Sunday evening, about 4km from the Causeway.

A video of the attack at a Shell station in Taman Pelangi was widely shared on social media, but police say the white BMW 5-series that carried the assailants used a fake registration number.

The video showed that the victim was stabbed and then run over twice by the car in the 7.30pm incident.

"We managed to trace the original owner of the registration number and we found that the owner had nothing to do with this case," Johor police chief Mohd Khalil Kader Mohd said in a statement yesterday.

The registration number was found to belong to a car owned by a 55-year-old man in Shah Alam, the Selangor state capital, according to The Malay Mail Online news site.

"Police have successfully identified the four suspects involved in the case and have stepped up efforts to locate and catch them," Datuk Khalil said.

Such brazen attacks involving what are believed to be gangland disputes happen regularly in Malaysia, with gunmen on motorcycles sometimes killing people in cars when they are stopped at traffic lights.

In October, two men in their 30s were injured in Johor's northern Tangkak town, after a man fired seven shots at them while they were in a coffee shop.

In the case on Sunday, police said the 44-year-old victim, believed to be known as "Ah Chiu", died of a "stab wound to the heart". A post-mortem was conducted yesterday by Sultanah Aminah Hospital.

Malaysian media reports say the victim had stopped his white Volkswagen car at the Taman Pelangi Shell station, while his wife was inside the vehicle. The white BMW stopped nearby and four men alighted and began assaulting the victim. He was dragged to the assailants' car but fought back.

An 82-second video clip of the incident recorded by a bystander showed that during the scuffle, an attacker stabbed him. Firecrackers were then thrown from the car towards where the victim lay.

The assailants' car circled the petrol station and ran over the man, before reversing and running over him again.

The car then sped out of the station, stopping briefly for one of the assailants to get in before fleeing.

The victim was seen conscious, media reports said, but was believed to have died while help was on the way.

Datuk Khalil told reporters at the scene that police found a stab wound on the victim's chest.

Media reports yesterday said that the victim's wife took his body away at around 2.10pm at the hospital's mortuary, after the autopsy.

Police, meanwhile, asked the public to stop speculating about the identities of the four suspects.

Johor Criminal Investigation Department chief Azman Ayob made the appeal after multiple photos of four men allegedly involved in the attack were circulated on social media.

"The public should stop circulating incorrect and inaccurate information online," he said, according to Bernama news agency.