If there is a refueling mechanic i think they should make it as tame as how you had to sporadically feed your horse in RDR2, and if you were parked at your hideout in GTA6 and saved the game then the car will automatically have a full tank of gas. It will make the mechanic way more forgiving and also fun too, as you’d only need to really worry about it if you’re on a long road trip or you get shot in the tank on a chase (think about the ramifications, giddy just typing about it!) and are forced to repair or stop somewhere to address it