Upgrading cars on the go, just like tuning and car swapping

This is already made possible in the Donut update, so why not enable it throughout the whole game.
We can already tune cars, even choose our perks.
I say we make upgrading and painting also possible.
As a matter of fact, the more features we can use whilst out and about in the world - the better!
Ideally, anything that´s possible in the safehouse should also be doable in the open world, more freedom= more fun!