The manufacturers give journalists brand new cars to track. I don't know where those cars go afterwards, but I do know that modern cars leave the factory with all tolerances in spec, so you should be able to "full send" a new car without too much worry.
Believe it or not those media cars sometimes go to auction and end up at used cars dealers. I know 2 100% proven examples of a white GTR NISMO and a red 2019 track edition that members of my owners club were interested in buying. I did a little digging for them and found out the white GTR was used for many reviews including randy pobsts Laguna lap for motortrend and the red car was passed around to multiple journalist was wrecked had different wheels put on and The buyer had no clue before I told them. I doubt the dealerships even knew about the history both were purchased at auction