Auto World 1:18 Scale 1966 Pontiac GTO Hardtop Hemmings Muscle Machines. Celebrate a true American classic with this beautifully detailed 1:18 scale 1966 Pontiac GTO Hardtop, part of the exclusive Hemmings Muscle Machines series by Auto World. Painted in a rich and radiant Copper Blaze, this collectible die-cast model captures the raw power and elegant design that made the GTO a legend of the muscle car era.