Dad Gary Ternent and his son Bobby Ternent used their BMW to murder former family friend John Avers after they fell out with him.
The duo have now been jailed for at least a combined 48 years.
The 59-year-old father and his 32-year-old son took Mr Avers, 59, to an Iceland car park in Dagenham, Essex, and dad Gary held him down as Bobby repeatedly drove over him.
Jurors were visibly shocked as they saw horrifying CCTV footage of the incident and heard the dying man’s blood curdling screams.
Judge Anne Molyneux described Avers as “a much-loved father of two daughters”.
She added: “He was the main part of their lives. Their pain and that of their mother is lasting…he will not be forgotten.”
She said the victim “was screaming and a neighbor heard him crying out: ‘Help me! Help me!’”
The judge said Mr Avers was already badly injured and described his “unimaginable terror” as Bobby took the wheel and drove over him repeatedly.
“This was a ruthless execution without mercy of a helpless man. His pain and anguish are immeasurable.” She added.
Bobby was jailed for life and ordered to serve a minimum of 25 years while Gary must serve a life term and at least 23 years before he can be considered for parole.
The Ternents claimed Avers was a “big time villain” who had threatened their family in a row over £40,000 and they were so terrified that they acted in self-defense.
But they were both unanimously convicted of murder after their story was dismissed as a “preposterous fairy tale”.
Avers’ family had wept in the public gallery as the verdicts were announced.
Jurors heard Bobby had set up the meeting with Avers on September 13, 2020.
He picked up the victim and Gary was already in the car as they drove to the back of the Iceland store on Whalebone Lane South, also in Dagenham.
Avers was allowed to get out – only for Bobby to deliberately run him over.
As he lay helpless and screaming in pain, Gary held Avers down so his son could drive over him again and again.
“Bobby and Gary Ternent together murdered John Avers by deliberately driving that BMW straight at him, running him over,” said prosecutor Bill Emlyn-Jones.
“With Bobby Ternent at the wheel, and Gary Ternent holding John Avers down on the ground in front of the car, John Avers was run over once; then Bobby Ternent spun the car around and ran him over again.
“Gary Ternent then ran to join his son in the car…they then ran their victim over a third time, and then a fourth time.
“And only then, satisfied that they had done enough damage, they drove away, leaving John Avers dying, or more likely already dead from the catastrophic injuries that they had caused him.”
CCTV from a nearby house belonging to Harroon Ibrahim captured the horrifying attack.
Mr. Ibrahim, who was at home that night, told police: “I still can’t believe that anyone would do that to someone.”
He ran out of his house after hearing screaming, said Emlyn Jones.
“He saw a large car and he saw that there was one person in it and in front of it from his vantage point there was a person on the ground with someone else holding him down.
“He says that there was some movement between the two men in front of the car but he couldn’t make out exactly what it was, whether it was punching or kicking.
“He realized that something was seriously wrong, so he ran to get his phone to call the police.”
“He saw the large car reverse out of its space and he saw the BMW move towards the other two men.
“He thought, as perhaps you would, that the driver was just trying to scare the person on the ground.
“He assumed that the car was going to stop.
“As he told the police, ‘I couldn’t believe what I saw next and I still can’t believe that anyone would do that to someone.’
“He watched in horror as the car ran deliberately over the man on the ground.
Ibrahim remained in his car and waited for police to arrive, after which he gave them an account of what he had seen as well as the recorded footage from his CCTV system.
Only Bobby gave evidence and he claimed after arguing about the £40,000 he drove at Mr. Avers because he had threatened his family.
He said he threw the money out of the window in a panic as he drove off, but police could find no trace of it.
Both Bobby, and Gary Ternent of Movers Lane, Barking, denied murder but were convicted by the jury in January.
Detective Chief Inspector Mark Rogers, the senior investigating officer from the Specialist Crime Command, said: “This was nothing short of a cold and calculated execution. What Bobby and Gary did to their supposed good friend was absolutely shocking and was extremely distressing for those who witnessed it and those who have had to watch the graphic CCTV.
“John was already lying defenseless on the floor, there is absolutely no excuse that can justify holding him down and then running him over not once, not twice, but four times. It is barbaric.
“I am pleased that the jury agreed with the overwhelming evidence we collected against Bobby and Gary and found them both guilty of murder. It has been a very difficult time for John’s family and friends but I hope the fact that the Ternents now face a lengthy stint behind bars helps give them a small measure of comfort and closure.”