When the man asked for water, the driver went to the boot to fetch a bottle - only to watch in horror as the man leapt from the back of the car, jumped in the front and took off.
"I chased the car a little bit down the road, as you do when you're in shock like that. Literally as the car went around the corner the ambulance showed up."
Ambulance staff stayed with the driver for a few minutes before police showed up.
The incident was captured on a dashcam, and in footage provided to the Herald the driver can be heard yelling out as the man speeds off.
In later footage police sirens can be heard as the car drives down the Northern Motorway towards the city.
Moments later the car hits road spikes and wobbles wildly, before coming to a stop near the Harbour Bridge city-bound, with the Sky Tower visible on the horizon.
The driver's car was badly damaged and is having its wheels and suspension fixed.
He said he expected it would be ready to use in a week or so and in the meantime he had been using a rental taxi.
"Luckily insurance have been very helpful."
A police spokeswoman confirmed police were called at 12.30am on May 3 and told a man had stolen a taxi after faking illness.
"A number of North Shore police units located the vehicle and spiked it, however the vehicle continued driving for some distance before coming to a stop.
"The alleged offender was taken into custody and taken to hospital claiming he had taken synthetic cannabis."
A 25-year-old faces charges of unlawfully taking a motor vehicle, failing to stop for police and dangerous driving.
He would have appeared in court later that morning, she said.
