I spoke with the guy who built the originals for Mad Max (1) for hours at the Stanley Hotel.
He told me of the extremely limited budget and the cheats used. He was an air craft mechanic and still tinkers today.
The week I visited they were working on an Austin Healey Sprite fitted with a baby supercharger and at the time was rebuilding the gearbox.
For the life of me I cannot remember his name. I bet he can still be found at the Hotel bar most days drinking coffee!

Personally I'm not into replicas, but I understand why they exist.