I’d like it if the game displayed some visual indicator on each car’s info card in my garage informing me that the car is (or is not) available for immediate re-purchase from the in-game shop using in-game credits.
This would differentiate between limited/exclusive cars and common cars that can be instantly replaced - which would help me avoid accidentally selling my hard-to-get cars.
There are way too many cars for me to remember how I got them all, and I’d prefer an in-garage on-screen indicator instead of backing out to check the shop or referencing external lists/spreadsheets.
(edit/follow-up)
I discovered after selecting the “sell” option from my garage menu for the 2020 Honda #73 LA Honda World Racing Civic touring car, the game displayed this confirmation message:
“This is an exclusive reward car, and it may not be possible to earn again. Are you sure you want to sell this car for 50% of its value?”
…But this car is available for me to buy from the in-game shop using standard in-game credits, so it’s not an “exclusive” car since I can instantly get another any time I wish.

I would prefer a visible indicator on exclusive cars’ garage photos/cards in addition to a confirmation prompt.
(Actually, I would prefer that there not be any cars that “may not be possible to earn again,” but it’s too early in the year to start asking Santa Claus for miracles.)