A method to reduce fuel consumption when driving a vehicle, wherein the vehicle comprises an internal combustion engine, and a gearbox that is settable to a plurality of transmission ratios, and the vehicle is configured to be driven in at least a first mode (M1) and a second mode (M2), wherein, when the vehicle is driven according to the second mode (M2), a reduced fuel consumption is prioritized to a larger extent at the cost of performance compared with when the vehicle is driven according to the first mode (M1). When setting the gearbox from a first transmission ratio to a second transmission ratio lower than the first transmission ratio that is one of the three lowest settable transmission ratios for the gearbox, the method includes comparing a torque (Treq) requested from the internal combustion engine after setting the gearbox to the second transmission ratio with a first torque (Tlim1), and driving the vehicle according to the second mode (M2) if the request for torque (Treq) from the internal combustion engine is below the first torque (Tlim1).