For Car Jump Challenge I built an arcade style car controller, I took a lot of ideas from various open source projects. Here’s a list of a few I’d recommend

Edys Vehicle Physics - its not open source but its a great starting point to write any type of vehicle controller, its pretty simple and easy to adapt.

Fabulous, on par with EVP, different style, slightly more complex https://github.com/JustInvoke/Randomation-Vehicle-Physics And a side project by the author https://justinvoke.com/games/the-fastest-meal-of-the-day/

https://github.com/SergeyMakeev/ArcadeCarPhysics Interesting, lots to learn from this one

https://supertuxkart.net/ https://github.com/supertuxkart/stk-code Not c# but the code is readable and its a really interesting project