I’m curious… will I be able to make an 80’s Nissan March Super Turbo engine? Yes, both turbo and a supercharger. en.wikipedia.org/wiki/Nissan_MA_MA09ERT
Lancia S4 rally car had twin-charging as well and AFAIK it will be around at some point
And more recently there was the VW 1.4 TSI engine.
Oddly, this is NOT unheard of though I’m not sure they will add it their going pretty far out of their way to get turbos in, let alone allow us to combine the systems should they make them… Maybe they will add in superchargers but I just want them to get campaign mode done first so shhh. xD… Though in really odd way… those two systems counteract eachother and make a need for a VERY strong block… because if your supercharger, produces 1000 HP, that means your engine needs roughly 2000 hp to provide your 1000 your enjoying, which in turns means you need a 2000hp rated block … add a turbo, and you need even moorrree because now your not only making 100-200 more horses, your also putting more strain on the engine, therefore again needing a MUCH stronger block and compression that is extremely low… like 6:1 lol just to keep it from blowing nice little holes in your block… now with that being said, the developers have to code in forumli for ALLLLL of that… yep… possibly in the far future is likely but now, not yet… 
/\ You obviously don’t have any idea how modern twin-charging works.
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Anyways, I really doubt it will be incorporated in the main game as it would cause hell with all the piping, let alone coding problems. Also the system isn’t really all that cost-efficient since the gains you get from twin-charging are minimal.
It’s not just about what’s efficient. Many people also want to recreate real life engines and/or create really insane/exotic stuff, just out of curiosity and for fun.