Hoyal said the incident began about 9:18 a.m. near 4600 South and Highland Drive.
"The victim pulled into the parking lot of the business where he worked. A white pickup pulled in behind him, a passenger got out, confronted him with a handgun. The suspect demanded his car, keys and phone," Hoyal said.
The driver complied and was not injured, watching as the thief followed by the pickup sped away southbound on Highland Drive in the gray sports car.
Multiple Utah police agencies were on the lookout for the carjacker and his accomplice.
At about 12:45 p.m., a tipster steered police to 200 West and Paxton Avenue (1180 South) in Salt Lake City, and more than a dozen Unified Police and Salt Lake City police units converged on the area.
When an officer spotted the car, the suspects led police on a chase along city streets before they entered Interstate 15 at 1300 South, then headed east on I-80, where they reached speeds of about 120 mph, Hoyal said.
The Porsche exited I-80 at 1300 East, then headed south toward the Brickyard area.
Officers found the car abandoned at about 1:20 p.m., the surrounded the area and searched until they flushed out the two suspects.
Hoyal said the men face possible charges of aggravated robbery, fleeing and possession of a stolen vehicle.