Filling a car in GTA 6 took about ten seconds in creator TGG's account of a Rockstar preview. That is his estimate of the demonstrated interaction, rather than an official fixed duration for every vehicle.
GamesRadar's report of TGG's vehicle deep dive describes a choice between repair and refueling at a gas station. Refueling triggers a short quick-time interaction and an animation of the fill-up.
The tank matters before the stop
Flow Games provides the more consequential example. During its demonstration, a stolen vehicle with less than a quarter of a tank ran out of fuel in a chase. Rob Nelson discussed a system intended to avoid constant interruptions, with a warning becoming relevant when fuel is low.
The same interview confirms that electric vehicles need charging and describes charging locations on the map. It does not supply a universal driving range, charging duration or fuel price.
A short refueling interaction can still matter if the car reaches empty at a bad moment. The new decision is therefore partly about choosing transport: a vehicle that is close, fast and easy to enter may still be a poor getaway option if it cannot complete the trip.
Why duration is only part of the question
Nelson's response to TGG acknowledges that players will have their own reaction to the system and emphasizes the speed of the demonstrated stop. That answers one concern about the time spent at the pump.
Frequency is a separate issue. Ten seconds once during a long drive feels different from ten seconds after every short journey. The preview accounts describe the intended balance, but the single example cannot measure how often ordinary players will need to stop.
As a design choice, fuel gives a stolen car another condition to inspect. Whether it becomes an interesting complication or an interruption will depend on how clearly the game communicates that condition during a hurried escape.
Our driving report covers how Rockstar says the vehicles themselves should feel.