It’d be nice to have a go-kart body, so we can try out some really small engines on it! Just make it really light, and I’m guessing a lot of cooling as well (engine is in open-air).
Thanks…
Ya know, Automation’s chassis system does not seem to be suited for this kind of stuff, sorry.
Plus: Have you seen go-kart covered with a roof?
Lotus Elise? 
I find the small modern mid engine body quite suitable for that. I’ve configerd one with a glue-ed aluminium chassis and polymer bodyshell and equipped it with a transverse 1.6 turbo engine with 200 hp and a basic interior. That resulted in a small rocket doing 0-100 in 4.9s and excellent handling.