Eve Smith and Darcy Ross, both 21, and Rafel Jeanne, 24, died in the collision, which happened on the A48(M) near the St Mellons area of Cardiff, in the early hours of Saturday, March 4.
Sophie Russon, 20, and Shane Loughlin, 32, who were also travelling in the white Volkswagen Tiguan remain in a critical condition in hospital.
The group had been to The Muffler social club in Maesglas, Newport, on Friday night and then travelled just under 40 miles to the Trecco Bay caravan park in Porthcawl.
A caravan at the holiday park where the group are understood to have stayed for a period of time prior to the accident has been cordoned off.
The PA news agency understands police are aware of a noise complaint made to the park’s security lodge about the group.
They left a short time later and were last seen at about 2am in the Pentwyn area of Cardiff having dropped off a sixth member of their group.
The man is said to be cooperating fully with the police investigation.
Investigations are still ongoing to establish the exact time of the crash.
South Wales Police said they are still working to “piece together” what happened.
In a statement the force said: “South Wales Police is continuing to investigate the fatal road traffic collision on the A48 in the St Mellons area of Cardiff.
“Our thoughts continue to be with the families and all those affected by this tragic incident.
“Specialist officers are carrying out a detailed investigation to piece together what has happened.
“Family liaison officers are supporting the families involved at what must be a hugely difficult time for them.”
Tributes were paid to the victims of the car crash in the Welsh Parliament on Wednesday.
Senedd speaker Elin Jones MS said: “On behalf of the Senedd, our sympathies are with the friends and families of Eve, Darcy and Rafel and our hopes are with Sophie and Shane for a full recovery.”
A member of the Senedd said there has been “a great deal of public distress following the crash” and “disquiet” among the families of those involved about the police handling of the missing persons investigation.
Peredur Owen Griffiths asked what role the Welsh government could play in ensuring police prioritising processes for missing persons are adequate to “ensure incidents like this can be avoided in the future”.
The Independent Office for Police Conduct (IOPC) has launched an investigation into the actions of South Wales Police and Gwent Police during the search for the group who were not found until just after midnight on Monday, March 6.