We highly recommend keeping your gas tank full whenever possible. Keeping your gas tank full helps signal to your guests that they should refuel before they return your car and makes it easier for them to know how much fuel to replace.
We ask that hosts have at least a quarter tank of gas in the car before the start of each trip. That way, your guest's first stop doesn't have to be the gas station.
If a guest forgets to refuel at the end of their trip, we're happy to reimburse you for the cost of refueling your car. You can read more here.