Abstract: The present invention relates to a fuel system as well as a method for controlling the same. More specifically, it relates to a fuel system of motor vehicles adapted to be powered by alcohol-containing fuels, and specifically by alcohol-containing fuels and by petrol, so-called Flexible Fuel Vehicles (FFV). These vehicles can be powered by fuels with varying alcohol content, and also by pure petrol. The fuel system according to the invention comprises a main tank (1) for fuel, a cold-start tank (2) with fuel which is sufficiently inflammable to be used in connection with cold starts, as well as fuel line system connecting these tanks to each other and to injection means of the engine of the vehicle, where at least one pump (8, 13) is adapted to transfer fuel through the fuel line system. Specifically, the invention relates to a system which is controlled so that fuel is transferred from the main tank (1) to the cold-start tank (2) when the alcohol content of the fuel is below a predetermined threshold value.