The phrase "larger fuel tank" refers to an increase in size or capacity of a vehicle's fuel storage container. This means that the car, truck, motorcycle, boat, airplane, etc., has been equipped with a larger gasoline, diesel, or other type of fuel holding compartment than it originally had. The purpose behind this modification could be to increase the range or distance that the vehicle can travel before needing to refuel, improve driving endurance without having to stop for frequent fill-ups, enhance performance by carrying more energy dense fuel, or simply accommodate a greater amount of fuel in case of long trips.