Just my 2 cents:
Cars and car's physics in GTSport by their very nature , are not connected with each others in a way to apply settings patterns.
For exemple , you will find a FR car reacting like a RR car , or a MR car showing more under steer than another FF car ....
Most of the cars in GTS , around 50%, have a good base tune , much more than in olders GT games , but there is still a too big proportion for a tuning APP doing the job.
For this happening , you'll need physics patterns and reliable physic conection between all cars.
Considering basic physic like:
Weight x power
Weight repartition
Grip level
Downforce level
But also mechanical's physic interpretation:
Tire's physics differents between 2 similars cars have to match.
How the torque and power are transmitted to the ground . (Differents results for same kind of cars) .... and a lot more parameters.
Perhaps the only solution would be an APP giving a note from 1 to 10 to several parameters and behaviors and on this base , applying a given setting through a tuning APP.
Anyway , the result would be very rough , just another base tune to be refined.
Just my humble opinion.