With offers closing on Sunday, the current owners will only sell all 13 together in an effort to preserve a piece of film history.
"They shouldn't be sitting in storage; they should be out there and getting the respect that they deserve," McKew said.
Although they certainly wouldn't "go for cheap", it was hard to put a price on the fleet, he added.
The vehicles are part of an armada of wild machines that burst onto the screen in the award-winning Fury Road, the fourth film in George Miller's Mad Max franchise.
The movie's success further cemented the cult status of the Australian action series and its title character, first played by Mel Gibson in 1979.
The sale has aroused interest worldwide, including from Las Vegas casinos and the Burning Man Festival, McKew said.
Sadly, none of the cars are street legal.
But McKew doubted that police would be daring enough to pull over a ride like the Gigahorse, molded out of two 1959 Cadillac Coupe de Ville and barely fitting into its temporary home at a Sydney warehouse.
"When I saw it start for the first time, I wasn't sure if I was having a heart attack or a bowel movement," he added.
