The regular fuel tank was 10.6 gallons, and the reserve tank was 1.3 gallons. From the owner's manual: "For vehicles with a fuel tap, the operating lever should be set at "Open". If the engine begins to "shutter" due to lack of fuel, just turn the lever right to "Reserve."
The owner of an old Beetle described what this meant in practical terms: "Of course, there was no way to check the gas level while you were driving, which meant that you could be straining down the freeway at 65 MPH one minute and windmilling down to zero the next when you ran the tank dry. So the VW designers gave the driver a little valve next to the foot pedals that you could work with your toe, which turned on a reserve fuel supply good for about 30 miles, which they figured was enough to get you to a gas station. So when the engine quit, the drill was to leave the engine in gear, cut into the slow lane, flip the valve with your foot and pump frantically on the gas pedal to restore the flow of gas. If everything worked, the engine started up again after about 5 seconds of terror; if unsuccessful, you cut onto the shoulder and coasted to a stop."
