Motor vehicle fuel system having multiple fuel tanks

A motor vehicle comprising:

• a fuel-consuming engine for propelling the vehicle;
• and a fuel system for fueling the engine;
• wherein the fuel system comprises at least a first fuel tank and a second fuel tank, each for holding liquid fuel for the engine, at least one pump for pumping fuel from the fuel tanks to the engine, a first valve mechanism through which fuel is delivered from the fuel tanks to the engine and which is selectively operable to at least a first position that allows fuel to be pumped concurrently from both the first fuel tank and the second fuel tank to the engine, a second position that allows fuel to be pumped from the first fuel tank, but not the second fuel tank, to the engine, and a third position that allows fuel to be pumped from the second fuel tank, but not the first fuel tank, to the engine, and a second valve mechanism through which fuel returns from the engine to the fuel tanks and which is selectively operable to at least a first position that allows fuel to return from the engine concurrently to both the first fuel tank and the second fuel tank, a second position that allows fuel to return from the engine to the first fuel tank, but not to the second fuel tank, and a third position that allows fuel to return from the engine to the second fuel tank, but not to the first fuel tank.