The company added 165 workers to its 2400-strong workforce at the Elizabeth factory late last year as it began the final pilot builds of its Cruze small car.
Holden also has a handful of marked and unmarked Caprice police vehicles undergoing testing in the US and has been getting strong feedback from local law enforcement testers.
Holden manufacturing executive director Martyn Cray says the company would not have made the investment without being confident.
"The police car is being tested by drivers in the US, they are the ones buying it and when we get an idea on how happy they are we'll be able to make more announcements - the police market is new for us so we're feeling our through the market.
"We've invested a lot of engineering resources and a lot of money in the (US) police program - we wouldn't have invested all that if we didn't think we had a fighting chance of getting that business," he said.
Acting SA Minister for Industry and Trade John Rau said the extra jobs was a positive development. "We're very pleased to have been able to partner with Holden and get this great outcome for the people of SA and in particular the people living in the northern suburbs, it's a great opportunity for them," he said.