Child restraints are being credited with saving the lives of two toddlers when the car they were in crashed into a bridge minutes after it was stolen from a Dunedin petrol station.

Police say a 25-year-old Dunedin man took the car with two boys aged three and 18 months in it while their father was inside a Dunedin petrol station about 10.20pm on Thursday.

They say he reached speeds up to 150km/h before crashing into an abutment on an overbridge on State Highway 1 near Mosgiel about 10 minutes later.

The two boys were unhurt but taken to hospital as a precaution.

The driver suffered a small cut to his head.

Police say it appeared the driver didn't know the children were in the car.

"It was extremely fortunate that these children were safely restrained in child restraint seats given the dangerous speed, road conditions and subsequent crash," said acting Senior Sergeant Tania Baron.

"There could have been a much more serious and tragic outcome."

The man is due to appear in Dunedin District Court on Friday on a number of charges including drink-driving, stealing a motor vehicle and dangerous driving.