Three men and a teenage boy arrested in connection with the murder of a garage owner for his Mercedes sports car have been bailed, police said.
The four were arrested over the murder of Harjinder Singh Bhurji (32), who died in a pool of blood after being stabbed when he refused to hand over keys to his black Mercedes CLK coupe.
His death was condemned by his family as a "senseless crime".
The men and boy detained, aged 17, 18, 19 and 20, have been bailed pending further inquiries, Scotland Yard said.
Bachelor Mr Bhurji was sitting in his sports car talking to a female friend when a robber opened the passenger door and dragged the woman from the car.
The victim, who lived in Ilford, east London, initially tried to hide the car keys under his seat but the robber threatened to harm his friend if he did not hand them over.
He was stabbed as he tried to retrieve the keys before the thief drove off with the car.
Mr Bhurji was pronounced dead at the scene in Stoneleigh Road, Ilford, after police were called at 1.10am on Tuesday.
The car was found abandoned in nearby Chingford at 2.45am.
Mr Bhurji's friend was found at the scene uninjured but suffering from shock.
Mr Bhurji's best friend Gurmit Birdi (32), said the victim's family was "distraught", while Mr Bhurji's uncle, Narinder Shargill, said the attack was unimaginable.
Mr Birdi, a British Airways cabin crew member, said Mr Bhurji had been due to act as best man at his wedding in India on November 1.
"He was a very nice person, he never did anything wrong," he said.