The back end of this original Fiat 500 has held a 580 horsepower Murcielago V12, a 3.0 liter Ferrari V8, and a 3.2 liter Porsche six. Basically, every engine ever made has been in there.
It was built by Oemmedi meccanica and is featured in Motor Head Magazine. As we can tell from the footage of this car on the track (with the Ferrari V8), it's a bit of a handful. Who cares! It's amazing.