Hamilton police Sergeant Paul Stanhope said the rollover happened about 2.15am Sunday at the bottom of the hills at Muntham on the Glenelg Highway between Casterton and Coleraine.

The 21-year-old Casterton female driver and sole occupant of the vehicle did not suffer any injuries but due to the nature of the accident was taken to hospital and remained there for observation.

Sergeant Stanhope said fatigue may have been a factor in the accident.

"The car flipped and there was some great work done by the CFA (Country Fire Authority) road rescue crew. The vehicle received extensive damage," he said.

"It's timely with the south-west receiving our first winter blast that all drivers check their tyres and drive to the road conditions," he said.