I am sure everyone is sick of the same old, low quality v8 engine sound for ALL of the cars that are made, whether it is a Prius, semi truck or any other car, they all use the exact same engine sound for everything. An idea I have is to add variety is too have adjustable cylinder count, stroke type, displacement, and rpm limit

rpm limit
This is pretty self explanatory, you would be able to choose a max rpm for your engine (probably in the range of 200-15000 rpm)along with being able to set an idle rpm (50-3000 rpm). This should allow you to do anything from a large ship engine to a high performance f1 engine, and anything in between

Displacement
Basically all this would do is scale up the engine model, increase torque and increase the max power, could be measured in cubic inches or liters

Cylinder count
This would should allow for any cylinder count from 1-18 cylinders in boxer, radial, vee, and inline configurations, or as an external you could add wankel rotaries or opposed piston engines, all this would do is change the engine size, affect displacement and change the engine sound.

Fuel type
All this would do is change the sound and torque, (gasoline vs diesel), not much else would change

This likely wouldn’t be achievable for 1.12, but maybe this could be included in a future update