Constable Mark Worth, an accident investigation specialist with Dyfed- Powys police, told the inquest at Brecon, Powys,that he concluded that the Porsche went out of control and slewed through 90 degrees before hitting the oncoming car.
He told the jury: "The Porsche used the Renault as a launching ramp. In my opinion the Porsche went out of control. The closing speed was probably around 150mph with the Porsche doing around 100mph."
The driving event, based at Llangoed Hall, a hotel nearLlyswen, was organised by Cardiff Porsche dealers Merlin (Cambrian) Ltd on 11 June.
Gavin Shaw, 30, an employee of Merlin, was at the wheel of a Porsche 911 Tiptronic taking Derek Redfern, 57, a businessman from Kingsbridge, Devon, on a demonstration drive. Karen Dalley, 22, was driving her Renault 5 returning to her job as assistant manager at the hotel.
The crash, in fine weather, closed the main A470 road linking north and south Wales for six hours. All three died instantly and the vehicles were engulfed in a fierce blaze.
Merlin (Cambrian) had assembled nine Porsches at the hotel for the day's demonstration runs. Ronald Harris, then general manager of the company, said they had invited "hand picked guests". He told the jury that when he heard of the crash he rushed to the scene. "The vehicles burst into flames. There was nothing that could be done," he said.
A motorist towing a caravan described how a Porsche overtook him when he was travelling at 50mph on a straight road. John Palmer, 65, from Ledbury, Hereford and Worcester, said: "I heard a whoosh and thought it was a low flying aircraft. But then a Porsche overtook me so fast that I couldn't even pick up its registration number." Other witnesses taking part in earlier sales test drives told of the vehicles' speeds.
Mr Redfern's son Oliver, a student at Cardiff University,was in the passenger seat on one drive. "I saw the speedometer reach 120mph," he said. Trisca Soper, a student from Abergavenny, was a rear seat passenger. "I looked over the driver's shoulder and saw the needle register 115mph."
The hearing is expected to conclude today.Reuse content