Carried in 165 often ancient vehicles, seven of them irreparably lost on the way, the small army stopped in Moree on Tuesday, on their from Lightning Ridge to Glen Innes.

Box Rallies founder James Freeman had the arguably bizarre idea after he lost both his parents to cancer in a twelve month period.

"Ninety per cent of the people here have a very similar story to me," he said.

"The rallies give them an outlet to be able to fundraise in a way in which they want to."

After ten years on the road, the 2019 mystery box crew had broken the record, raising over a million dollars in eight months of tough yakka.

Mr Freeman said through 2019 they will raise at least $5 million all told.

"Because of that we are the largest fundraiser for the Cancer Council in the country," he said.

"And we now are the second largest contributor to cancer research programs after the government.

"And it's because of these people."

Drivers learn of the day's destination the morning of a drive, though they know the rally will start and finish in Byron Bay. One organiser said she had to find a way of strongly recommending drivers pack for cold weather without giving the route away.

Many of the quarter-century-old cars do not make the whole trip across "the roads less travelled", Mr Freeman said. They lost seven vehicles completely written off and sent to the great car yard in the sky, but a large proportion have had mechanical problems of some sort.

He pointed to the six cars in his team. Four had been knocked out.

"And that's normal.

"They break down; we fix them and press on.

"Some of them that we can't fix on the side of the road, then we'll wait for one of my support teams."

He said they had drivers from every state and territory, as well as California, New Zealand, England, Florida, and more.

The rally ended in Byron Bay on Wednesday, with all cars crossing the finish line except seven which were pronounced dead during the course of the rally.