A fire service spokesman said the car was about 3m down into the drain when emergency services arrived, after being called at 6.18pm.
The roof had to be cut open for the man to be extricated and the man climbed out via a ladder.
He was not reported injured, although police said he was taken to hospital and was to undergo drink-driving testing.
Emergency services also attended a crash in which a trailer detached from a car and struck a van near State Highway 2's Devil's Elbow and between the highway intersections with Aropaoanui and Mcintyres Access roads, early on Saturday afternoon.
Police communicatins centre staff understood St John Ambulance staff assessed and treated occupants at the scene.