The inquest heard a police speedometer showed the car it was chasing reached speeds of up to 126mph
A teenager who had taken cocaine drove the wrong way along a motorway and into another car, killing himself, two friends and a couple, an inquest heard.
Driver Christopher Beresford, 18, and two others who had been in the car had taken "a lot of drugs", said a witness.
Police chased their car before it went onto the M4 at Newport in September 2007, the city coroner's court heard.
James Stafford, 69, and his wife Bridget, 70, died as they travelled home to Surrey from an Irish holiday.
Mr Beresford, Lee Maggs, 23, and Sam Case, 19, all from the Newport area, were in a Ford Mondeo when the crash happened on 17 September 2007.
Wayne Maggs, Lee Maggs's brother, had earlier been in the car with the three who died and another man, James Burnett, who survived.
Christopher Beresford, who was driving, had taken cocaine
In a statement read to the court, he said they had been "driving about" in his his brother's car, adding: "We'd done a lot of drugs, sniffing cocaine, me, Sam and Chris".
They were "messing about and two mountain bikes got stolen from front gardens" in the Penhow area when police arrived.
The others ran away but he was left behind while hiding in a garden. The court heard that Wayne Maggs had called a taxi to go home and it was unable to get onto the motorway.
"I had a feeling straight away that it was them," his statement added.
Plume of smoke
Pc Nathan Price said in a statement read to the court that he and a colleague were called to a street in the St Julian's area of Newport at about 0150 GMT by a couple reporting suspicious activity in their driveway.
Pc Price said he and his colleague discovered a burgundy Ford Mondeo parked half-on a pavement and the engine was still warm. A traffic unit was called to the scene.
Pc Price said he believed the group would return to the Mondeo if they thought the police had left the scene, so they parked nearby.
About five minutes later, he said, they noticed a vehicle travelling "at considerable speed", which they believed to be the Mondeo, followed by the traffic vehicle.
He said they followed the two cars along the A48 towards the Coldra roundabout and could see a plume of smoke coming from the motorway.
At no time did I deem that pursuit dangerous
Pc Richard Wyatt, who was driving the traffic car which pursued the Mondeo
Pc Price said they drove onto the motorway and could see there had been "a very serious collision".
He said the Mondeo was on its roof and appeared to have been travelling in the wrong direction and had collided with an oncoming vehicle.
The officer said the both men sitting in the front of the car were dead. But he could hear a voice shouting and screaming from inside the car, which turned out to be James Bunnett, and he helped him away from the scene.
Mr Bunnett was "clearly traumatised" and had multiple injuries, he said.
The officer added that the man and woman in a red Volvo which was involved in the collision were also dead.
The inquest jury was shown a video of the chase filmed by an in-car recorder which showed the pursuit reaching the Coldra roundabout, the Mondeo taking the slip road the wrong way onto the M4 and the traffic vehicle standing down.
Pc Richard Wyatt, who was driving the traffic car which pursued the Mondeo, told the inquest: "At no time did I deem that pursuit dangerous."
He said they matched the speed of the Mondeo to monitor it, rather than gaining on it, so there was no pressure on the driver to travel at high speed.
Shaheen Rhaman, representing the Stafford family, asked why he was interested in the Mondeo.
Pc Wyatt said there had been numerous burglaries in the area and it was an unusual vehicle to be in the area.
"We wanted to stop it to find out who was in it and why it was in that area," he said. "When it failed to stop that was an arrestable offence."
The inquest heard that Mr Stafford was from Ayrshire, and Mrs Stafford was from Achill Island in the Irish Republic.
They were returning from their holiday home on Achill Island to Thornton Heath, in Surrey after catching the ferry from Rosslare to Fishguard, Pembrokeshire.
Mr Beresford and Lee Maggs were both from Duffryn, Newport, while Mr Case came from the Maindee area.
An Independent Police Complaints Commission investigation began after the crash.
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