That doesn’t make sense. Rescanning a car can mean adding it as a new car.
Gran Turismo has suffered from the exact same problem in the past. They introduced new cars which they called Premium. There was a bit too noticeable difference between Premium and Standard cars to the point where it even became a meme. Over time they were able to solve this and make EVERY car Premium in Gran Turismo 7. Forza can do the same, and should. Using assets that are 10-15+ years old in 2023 is completely unacceptable!
Info about Premium cars and about the amount of time it takes to develop a Premium car: