Repurposing the game to support that kind of mods would probably be hard and time intensive. It’s just pointless really.
As much as I understand the desire to have every feature ever available, especially since the game is a sandbox for now, you can have tons of fun with what is already there.
Invest some time in building a lore company for the forums and you’ll see that the need for new features will decrease as you start enjoying building cars for a purpose.
I cannot stress enough how much starting to roleplay there has refreshed and renewed my interest for the game.
The community here is amazing and you’ll soon find you don’t really lack options - and yoi’ll learn much !
Just sparking a community that can create data that could be used for the game could speed up engine configurations like boxers wankels and flathead engines.
I could write a long paragraph about this, but that’s been done before, so the short answer is: not happening. Engines are a lot more complicated than you seem to think and also have a lot of proprietary code that the devs will not be making public.
I’m surprised how long are some dead horses beaten here. It seems that searching and reading are some magic arts.