The crash occurred on Main North Rd near Research Rd just after 11.30pm on Friday.
The driver and sole occupant, a 29-year-old man from New South Wales, was taken to the Royal Adelaide Hospital in a serious but stable condition.
About 90 minutes after the initial incident, a Mazda station wagon crashed into a stationary police car that was diverting traffic away from the crash scene.
Fortunately, no one was injured in the second crash but both cars were extensively damaged.
The driver of the Mazda, a 66-year-old Golden Grove man, will be interviewed by police.
Anyone who may have witnessed the incident is asked to call Crime Stoppers on 1800 333 000, or online at www.crimestopperssa.com.au