The Suzuki sedan smashed into a tree at Brooloo, about 40 kilometres inland from Noosa, on Monday afternoon.
Police were called to the crash at the corner of Callemonda Road and Mary Valley Road about 2pm and arrived to find a man dead in the front passenger seat and a woman in the back.
The 61-year-old driver was airlifted to Sunshine Coast University Hospital with serious injuries.
Later in the day, Nambour criminal investigation branch detectives arrested him and placed him under police guard in hospital, where he remained early this morning.
Police appealed for anyone with dash cam footage or other information to come forward.
