you won't realize it without being informed, but, this an absolutely regular dolly (hand truck), made into a regular go-kart, by a regular guy. He did something quite extraordinary though... he shared all the links to the parts sources, and the how to make it video!

 Watch this unit go from a regular hand truck to a fully functioning four-speed 125cc go-kart 

https://www.rideapart.com/news/738225/diy-hand-truck-go-kart-build/