A couple were beaten unconscious and their car stolen in Onehunga on Saturday night, and police are still looking for the man who did it.

Authorities have established the stolen Toyota Vitz - registration HYT799 - was involved in a second incident just an hour later, where a family car was rammed at a Z petrol station on Great South Road.

Police say the mum, dad and children inside the car were deliberately driven into twice.

The stolen car hasn't been found yet, but police are looking for a second offender who's been spotted in the passenger seat.