William Payne was driving the car in North Hanover Street, near Buchanan Bus Station, when he collided with Mhairi Convy, 18, and Laura Stewart, 20, who were students at Glasgow College Of Commerce. Both women later died at the city's Royal Infirmary.
Mark Hopwood, then 36, was thrown on to the road and also injured but survived.
Witness Gary McGinley gave evidence at Glasgow Sheriff Court at an inquiry into the deaths on December 17, 2010 of Ms Convy, of Lennoxtown, Dunbartonshire, and Ms Stewart, of Cumbernauld, Lanarkshire.
He told the court he came out of the North Hanover Street exit of the Buchanan Galleries car park and was at the traffic lights when he saw Mr Payne's vehicle approaching him in the opposite carriageway.
Mr McGinley said: "My initial thought was the speed the vehicle was travelling."
He added: "I thought it was a ridiculous speed to be travelling in the inside lane."
The witness said he then 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."
Mr Graham asked if he saw anyone being hit and he said he did.
Mr McGinley told the inquiry: "It was a bit of a frenzy. I knew after the event three pedestrians were struck, but at the time it was hard to distinguish how many there was."
Mr McGinley said he went to see the girls on the ground, then the driver of the car, before going to Mr Hopwood.
Mr Graham asked what state the two girls were in. Mr McGinley replied: "Their bodies were slightly twisted and in a bad way. It was quite gory to see.
"I ran over to the driver, he was just facing ahead, pan faced, eyes fixed. 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 court also heard from Mr Hopwood, who was hit by Mr Payne's car during the collision.
Mr Graham asked him what happened when he crossed the road in North Hanover Street. He said: "That's when I noticed the car on the pavement heading towards me."
He said: "As I was turning away I am assuming the front side hit me, from what I have worked out."
Mr Hopwood said the car was travelling about 50 or 60mph before hitting a grass verge. Although he did not see the car hit anyone else he said he saw someone else lying on the road.
Another witness, Darren Bell, told the court he saw one person "up in the air" who landed in the middle of the pedestrian crossing, another who was "dragged" and further away a man was lying on the ground.
Asked what gender the people were he said: "The one that was in front of me was female, the one that had been dragged away was a dark haired female and the chap, obviously, was male."
John Hutchison, 65, who also was at the scene, said he turned off the engine in the Range Rover as the car was against a pole at an angle with the wheels still turning.
He said he heard Mr Payne say, "I'm not well" when a police officer arrived at the car.
Mr Hutchison also said he saw a mobile phone lying at the car and got angry because the girls had been hit.
It was suggested to him that in a police statement given to police at the time he told Mr Payne, "You stupid b****** you nearly killed them."
Mr Hutchison said: "Now you mention it I probably did. I totally forgot about that."
Constable Dawn Lindsay, who spoke to Mr Payne after the incident, said he told her he had slipped that morning.
She also told the hearing he said he had suffered blackouts dating back to 2007.
The hearing before Sheriff Andrew Normand continues.