Senior Sergeant Anthony Bond said a vehicle was seen swerving and speeding in Macandrew Rd, South Dunedin, at 6.45am on Saturday.
The car was travelling at 100kmh in a 50kmh zone before it crashed into a parked car.
The driver ran off and police have not been able to find them. An investigation is continuing.
An hour later, a 21-year-old man was driving east along Allandale Rd in St Clair when a dark-coloured car drove down the hill towards him, crossing the centre line.
They hit the side of the man's vehicle before speeding away, Snr Sgt Bond said.
The driver did not stop to check if the man was injured or to exchange details.
No injuries were reported.
Anyone with information about either crash was asked to call contact police on 105.