The crash happened near the Prebensen Drive/Hawke's Bay Expressway intersection.
Both drivers were trapped and the Fire Service cut them from their vehicles.
The driver of the other car, a female in her 20s, was later discharged from hospital.
Senior Constable Cory Ubels said investigators would like to speak to witnesses to the crash. "I would also like to speak to the people that were at the crash scene before any emergency services arrived," Mr Ubels said.
Police had not yet considered whether charges would be laid.
He said anyone who may have seen a silver Nissan Primera sedan driving in the Tamatea area near Westminster and Tamatea Drive just prior to the crash, should get in touch with police on 873 0500.