tl:dr: some visual engine upgrades and swaps
Forza games have always given you some level of visual customization with body kits, aero, brake and chassis upgrades. performance wise, you could just keep all the cars bone stock models and just change the handling characteristics. but forza goes the extra step to show how your upgrades look. what if the same treatment was applied to the powertrain?
I think it would be really cool if our engine upgrades and swaps would be made visual to the car we’re building.
example: if we have a 2010 camaro SS with its NA 6.2L V8, and install a roots style supercharger on top of it, i’d love to be able to see it in forza vista mode. likewise for single or twin turbo upgrades and centrifugal supercharger upgrades.
the models already exist for each part individually (many cars have turbos, roots blowers, and cars like the HW mustang even have the centrifugal procharger as well), so being able to put a whackin big turbo under the hood and being able to actually see it would really help with immersion and progress that our engine tuning does more than make bigger vroom noises.
likewise, sensible engine swapping could also have a degree of visual implementation. so like a car with enough engine bay space to fit the large 8.4L v10 viper motor could be dropped in easily. for the more wacky engine upgrades though i’m not sure how you’d get around it, like v12 swapping a boneshaker probably wouldnt make sense since the stock motor already sticks out so much. it’s very blatantly obvious when you take the 2cyl Morgan 3-Wheeler and go to swap the engine to literally anything else and it looks identical to its stock motor despite being now several classes higher.
there’s a lot of potential with an idea like this, such as customizable turbo placement or further engine bay customization, but i am aware it’s a very advanced challenge to implement. same for driveline swapping, being able to see the axles change models when you go from rwd to awd would just be awesome to see.
even being able to only do even a little bit of this visual customization to a select few cars would be a great start. it would propel the already vastly improved tuning menus and interactions to even greater heights.