I would like to see things such as turbos, superchargers, and see the mechanics of vehicles expanded upon.
I would guess that by catadda time all gasoline motors will be supercharged. Even today more and more of the new ones are.
Diesels are by default already ofc 
EDIT
If you mean engine tinkering… weell, i don’t believe it will be that easy to realistically implement and balance.
Any specific ideas on how to do it?
Maybe make the turbo reduce engine power somewhat, at lower speeds? They should both increase gasoline consumption. I’m no gearhead, but would like to see these additions, making car modification even more expansive.
Hi mechanic here, realistically its not hard just time consuming. Implementation wise i wouldn’t how how to put it in the game. But in real life you can put on super/turbochargers on yourself easy it just take time when you do it by yourself. I don’t know were you read that most engine come that way, yes super/high-end sports cars do, but most everyday cars don’t.
I did not say that today most engines are turbocharged, only that in the future (10-20 years later) i would expect them to be.
That’s because, to my knowledge, turbocharged engines are much more frequent today than 10 years back, and the trend is increasing…