Not really how I like to manage things, unless I have no other choice. I like having multiple of a certain car for certain classes, race types and/or tasks as it makes it easier for me to pick car on the fly that I know is set up how I want it, rather than hoping that I remembered to put the right tune back on one car from the last time I used it. I also like to visually customize cars to fit their "archetypes," primarily so it's easier for me to ID them, but also because I like having vehicles that "look the part," so to speak.
On that train of thought, something I've wanted/need to suggest to PG/Turn 10 for a while is to allow players to make "folders" for cars that they own, so that users can organize cars in ways that they see fit outside of the regular filters and sorting systems. As an example, I would put a Clio Williams in an "90's Rally" folder along with the 22B and Evo 3, since it has Rally Visual Upgrades available, despite being a Retro Hot Hatch. As I understand it, GT7 has something along those lines by giving cars hastags, but I don't exactly know how that works in the game as I don't own it.
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Edit: Also, the Viper FE is as hilarious as it is a pain to drive. Thing's an understeering nightmare, but it's basically an overpowered Dune Buggy that can knock down trees at 200 MPH without too much complaining.