A minor incident inside the Ministry of Sound nightclub led to "breathtaking lawlessness" in which a man was nearly decapitated, the Old Bailey heard.
Gary Johnson, 25, died instantly when he was deliberately mowed down by a Mitsubishi Shogun 4x4 in August last year, it was alleged.
He was struck on the pavement opposite the club, thrown into the air, carried on the bonnet and had his head partially decapitated against a wall.
Mr Johnson's friend Dwayne McPherson took out a gun and fired several rounds at the Mitsubishi driver Ranjit Nankani, the jury heard.
Nankani escaped death when only one bullet struck him, said Aftab Jafferjee QC, prosecuting.
He added: "This case is about breathtaking lawlessness on the streets of London, where comparatively minor incidents inside a busy venue were responded to with murderous violence."
Nankani, 30, of Croydon, south London, denies murder, and McPherson, 28, of Sydenham, south London, denies attempted murder.
Mr Jafferjee said many people were at an event at the Elephant and Castle club in the early hours of the bank holiday.
The defendants were in their own groups and a row broke out which ended in people, including Nankani and his friends, being thrown out.
McPherson and his friend Mr Johnson left at 4.30am and did not see Nankani sitting in his Shogun outside, said Mr Jafferjee.
He said that "in a staggering act of revenge and/or retaliation", Nankani's car mounted the pavement, accelerated and struck Mr Johnson.
"He'd achieved the object of his terrible act of revenge," added Mr Jafferjee.
The car had gone on to collide with parked cars, trapping Nankani inside.
Mr Jafferjee said: "Now it was McPherson's turn for revenge. He pulled out his gun and fired several rounds at Nankani.
"He was going to kill Nankani in revenge for Nankani killing his friend."