Some engine part suggestions
Continuing on from the 'different style' type of thing, where's the love for twin-scroll turbos? Or variable geometry? Or single turbo on v8 and v6? These variations I see would also add some nice design options for different cars in different economy's or targeted brackets.
And one other thing I've thought of - boost by gear/speed. Specifically for tuning the engine once it's in a car (i.e. dyno tuning - another thing that I see should be added as engine performance changes when it's popped into a car), so you could slowly ramp up boost for better grip, constant(-ish) acceleration among other things.
Just some suggestions I think would be great inclusions into the game.
Also, first post!