Some cars have an automatic gearbox. the Pikes Peak VW has an electric engine, and Forza didnt give it a petrol engine “just because”.
To allow more authentic car builds, automatic, and sem-automatic geatboxes should be performance components that can be purchased in place of regular gearboxes and they would enable autmatic behavior regardless of the difficulty setting - with an associated weight penalty.
I would see this as an option. Allthough I cannot imagine people to choose a automatic gearbox for performance.
My proposal would be:
When you choose manual shift w/ clutch
Cars with DSG or other dual clutch transmissions should override manual w/ clutch (so when you usually shift with clutch in game you should not be able to use it)
when upgrading to the best spec transmission you get a sequential gearbox allowing you to shift without clutch but you still have the clutch pedal in the car so you can operate it still. Clutchless shifting but the option to clutch kick when needed, and for driving away/ rev match downshifting.
Sounds like an interesting idea. No idea how it would tbh but it sounds good and i would like to see this.