Abstract: A spare tank system for a motor vehicle is provided which may conveniently be coupled into the normal fuel line of the vehicle, and which comprises a conduit in which a valve and a fitting are mounted. During normal operation of the motor vehicle, the valve is in a first operating position, and the fuel from the normal fuel system flows through the fuel line and through the conduit to the engine without being impeded in any way. One or more closed cylinders, or other pressurized containers of fuel, such as gasoline, are also provided which may normally be carried in the trunk of the vehicle. Should the vehicle run out of gas, the valve is set to a second operating position, and the nozzle of the container is inserted into the fitting, so that fuel from the container may now flow through the conduit to the engine, with the normal fuel system being shut off.