William Payne was driving his 4x4 in North Hanover Street in Glasgow city centre when he collided with Mhairi Convy, 18, and Laura Stewart, 20.
He also injured Mark Hopwood, 36, who was thrown on to the road but survived.
At Glasgow Sheriff Court, eyewitness Gary McGinley gave evidence at the inquiry into the deaths of Miss Convy and Miss Stewart.
He told the court that on December 17, 2010, he came out of the car park at John Lewis further down the road and was at traffic lights when he saw Mr Payne's vehicle approaching him in the opposite carriageway.
Mr McGinley said: "I thought it was a ridiculous speed to be travelling in the inside lane."
The witness said he realised it was not the inside lane the car was driving on, but the pavement with the "engine revving".
Asked by procurator fiscal depute Jim Graham what he saw when it came down the pavement he said: "There was a collision once he came down to the traffic light area."
"It was a bit of a frenzy.
"I know after the event when I stopped the car there were three pedestrians struck but at the time it was hard to distinguish how many there was."
Mr Graham asked what state the two girls were in and the witness said: "Their bodies were slightly twisted and in a bad way.
"I ran over to the driver. He was just facing ahead, pan faced, eyes fixed."
He said: "I asked 'you okay, you okay pal? No response from him.
"He looked physically okay, he was sitting back in the vehicle and the window was open."
The hearing before Sheriff Andrew Normand continues.