Need Help Car Uprade System!

Hello !
I am making a Upgrade System for my Car , i am using scriptable Objects to store car information into asset file and each car having its own asset file , file is storing all the data , but the problem is I can not figure out how to Apply changes to player Car ,
1 : I have to know which upgrade type is selected
2 : after getting the required upgrade type use that information for my UI left right button to select upgrade…
i know im not good at english but if anyone can help me that would make my day as i have busted my head and can not figure

@Wolvorine_911 There are multiple ways to store information in unity i suggest using a seriazable class, a json file or any other mean such as SQL/SQLite to save and load the data and load for the player, the selection can be as simple as an ID (integer) a name (string) or an enum after the button being clicked check the selected ids and save that information into ur data storage.