People living on an upper level of the block of shops were forced to flee as the fire took hold.
A resident of the flat above the store who did wish to be named said she was woken by fire alarms and shouting.
She said that when she opened the door after coming down the stairs, a flame burst from the car.
“We are three people in the flat and thank God one was a little slow.
“If I had been a little bit earlier, it would have been much different.”
She said everyone was still in their pyjamas when they had to evacuate.
“I cannot believe how the day can go. Within seconds it could have been different. I’m just happy.”
The owner of Infinity Clinic, who wished to stay anonymous, said this was the fourth time this year her business had been targeted for the expensive equipment it used.
She said she got the “devastating call” at about 5.30am and arrived to see a “black hole” where her store once stood.
The store owner said this year alone, people had broken through windows and stolen “thousands of dollars” of equipment, and caused costly damage.
“They smashed all our screens with a screwdriver,” she said.
“I can’t believe that there are people like this ... these kinds of people who would do this to another human being.
“We are all just trying to make a living and then when this economy is already hard enough.”
She said she was unsure how much this damage would cost her or if she would ever be able to open her business again.
A Fire and Emergency spokesperson said firefighters were called to a fire in Esplanade Road, Mt Eden, at 5.20am after a car crashed into the building and sparked a fire.