Their deaths from cancer, within 12 months of each other, led him to launch the Shitbox and Mystery Box rallies, the latter leaving Dubbo Showground at 9am on Saturday.

Mr Freeman, 42, of Adelaide, reports that the rallies are the largest fundraiser for the Cancer Council in Australia. In the past eight years they have raised more than $12.7 million for cancer research.  So far almost $700,000 has been raised by the 300 people in 150 old cars taking part in the 2017 Mystery Box Rally that will return to Dubbo on Wednesday afternoon.

At the showground on Friday, Mr Freeman said the benefits of the rallies extended beyond raising money in support of “great research projects”. “For the most part people get involved because they have a similar story to mine,” he said. “I started the rallies because I lost both of my parents to cancer. It was obviously very traumatic and very difficult.”

READ MORE: Good mates rally against killer disease.

Mr Freeman said participating in the rallies helped in the grieving process. “Everyone has an absolute ball but they (the rallies) give so much more to people,” he said. “People get really close and.. are able to talk about what they have gone through.”

Mr Freeman’s mother Susan died from bowel cancer in 2007 and his father John from prostate cancer in 2008. “They were really wonderful people, really loving, and I miss them an awful lot,” he said. What would they think of his tribute to them and all others taken by the disease? “Mum would have thought that the name of the big rally was ghastly but she and Dad would be proud,” Mr Freeman said.

The Shitbox Rally is capped at 250 teams and the Mystery Box Rally at 150. In the 2018 Shitbox Rally cars worth $1000 will travel across “formidable roads” between Brisbane and Darwin. The Mystery Box Rally takes 25-year-old cars and their drivers along a mystery route that begins and ends in the same place. On Saturday morning Mr Freeman will give teams from across Australia including Perth the map for the first day of travel in the 2017 Mystery Box Rally.

To donate to a team visit www.mystery-box.com.au.