The engine should look different for example, when you swap a I4 for an I6 or a V6, the engine looks exactly the same when you open the hood.
They can just import the engine model from the car that uses the engine and replace the stock engine with the other engine model. I know it’s possible
I say they focus on modelling the cars correctly before bothering even modelling engines at all.
Unless they can model all the parts such as showing a turbo that’s added or intake or like you say showing the engine swap I think time could be spent elsewhere… good idea but just gives more excuses about time being a factor for anything they do and why a car that could take 3 months takes 6 months to add and if any mods done to engine it locks the engine bay anyway
They would need to make sure that every engine fits every engine bay of every car and looks at least half-decent… Too much work, I agree that time could be spent better elsewhere (maybe on fixing older models?)