The accident happened around 6:45 a.m. at the intersection of 23rd Street and Oregon Avenue.
Police say the 1999 Pontiac traveled at least 55 feet into the store before coming to a stop.
William DiBruno was just leaving the nearby gym when he heard the crash.
"I heard a big bang. I thought it was an unloading truck. I come outside, there's a car parked in the store," DiBruno said.
The driver was transported by medics to the Hospital of the University of Pennsylvania in cardiac arrest with no vital signs. He was later pronounced dead.
The cause of death has not been officially determined. It is also not known if the man went into cardiac arrest before or after the crash.
The driver has not yet been identified. Police say the victim has a history of heart attacks, but it's too early to say if that's what caused him to lose control of the car.
"He had a disabled vet tag. He had to be a vet. That's a shame," said DiBruno.
Employees of the store that was damaged, Rainbow clothing, gathered outside for hours.
"My thoughts and condolence are with the family, but I don't know," said Assistant Manager Malika Britt. "I don't know when I'll be back to work."
An autopsy is scheduled for Saturday.