Driver dies after car rolls on SA highway

South Australia's holiday road toll has increased to four after a driver was killed in a single car crash on the Eyre Highway.

The driver and sole occupant of the car died after their vehicle rolled 53km east of Ceduna on the Eyre Highway about midday on Friday.

Police are investigating the circumstances of the crash.

* The AAP national road toll period runs from 0001 December 23, 2016 until 2359 January 3, 2017, local times.