We have a local man here that used to display at the Glenmoore Concourse show. He would build around 1/5 scale cars with full working engines and transmissions.
He has repo Small block Chevys, Flat Head Fords and even V12 Ferraris engines. Some had working superchargers. He had a few chassis all welded together with full suspensions and some with bodies. It was a real joy watch these things fire up and run. The work and skill that goes into this stuff is amazing to me. Also the tool you need dedicated to this is not cheap either.