According to the Lang Lang town community website, since operations began in 1957, Holden test drivers and engineers have clocked up over 111 million kilometres in evaluating prototype, pre-production and current production vehicles on the Proving Ground's varied road system. A total of 454 cars have made the one-way, 100 metre journey into its concrete crash barrier.
Advertisement from Port of Melbourne Quarterly, January-March, 1966. Page 10. If you are unsure what they do at a Proving Ground, click on this image to enlarge it, and it will tell you.
The Proving Ground has a circular, banked high-speed track, a network of ride and handling roads, rough tracks, a twist course, a "rattle and squeak" track, dust road, test hills, a skid pad as well as mud and water baths. These roads and tracks take up only a small part of the land. The majority of the site is still natural bushland and is a fauna and flora habitat, with over 53 bird species recorded and 140 plant species.
Advertisement from Port of Melbourne Quarterly April-June 1966. Page 40, showing an aerial view of the Complex.