An automatic manual transmission for a car provided with an internal combustion engine; the automatic manual transmission comprises: a mechanical gearbox provided with: at least one primary shaft, which is adapted to receive a torque from a drive shaft of the internal combustion engine, at least one secondary shaft, which is adapted to transmit torque to drive wheels, a plurality of pairs (I, II, III, IV) of gears (16, 17), each of which has a corresponding transmission ratio and comprises a primary gear mounted on the primary shaft, and a secondary gear mounted on the secondary shaft which permanently meshes with the primary gear, and a plurality of locking devices, each of which is mounted on the primary or secondary shaft (14; 15) and is adapted to be actuated to lock at least one corresponding gear (16; 17) to the primary or secondary shaft (14; 15) itself; a plurality of first actuators, each of which is coupled to a corresponding locking device to actuate the locking device; a variable ratio transmission device which is arranged upstream of the primary shaft and is adjustable to have two different transmission ratios: a first unitary direct drive transmission ratio and a second multiplying transmission ratio; a second actuator, which is coupled to the transmission device to vary the transmission ratio of the transmission device itself; a clutch, which can be opened to interrupt the mechanical connection between the shaft of the internal combustion engine and the drive wheels and is separate and independent from the transmission device; a third actuator which is coupled to the clutch to open and close the clutch itself and is driven by the control unit; and a control unit, which controls in coordinated manner the first actuators of the locking devices, the second actuator of the transmission device and the third actuator of the clutch to shift gears by combining a transmission ratio of the transmission device with a transmission ratio to obtain a corresponding gear of the automatic manual transmission; the automatic manual transmission is characterized in that the clutch is arranged downstream of the secondary shaft of the gearbox. a mechanical gearbox provided with: at least one primary shaft, which is adapted to receive a torque from a drive shaft of the internal combustion engine, at least one secondary shaft, which is adapted to transmit torque to drive wheels, a plurality of pairs (I, II, III, IV) of gears (16, 17), each of which has a corresponding transmission ratio and comprises a primary gear mounted on the primary shaft, and a secondary gear mounted on the secondary shaft which permanently meshes with the primary gear, and a plurality of locking devices, each of which is mounted on the primary or secondary shaft (14; 15) and is adapted to be actuated to lock at least one corresponding gear (16; 17) to the primary or secondary shaft (14; 15) itself; a plurality of first actuators, each of which is coupled to a corresponding locking device to actuate the locking device; a variable ratio transmission device which is arranged upstream of the primary shaft and is adjustable to have two different transmission ratios: a first unitary direct drive transmission ratio and a second multiplying transmission ratio; a second actuator, which is coupled to the transmission device to vary the transmission ratio of the transmission device itself; a clutch, which can be opened to interrupt the mechanical connection between the shaft of the internal combustion engine and the drive wheels and is separate and independent from the transmission device; a third actuator which is coupled to the clutch to open and close the clutch itself and is driven by the control unit; and a control unit, which controls in coordinated manner the first actuators of the locking devices, the second actuator of the transmission device and the third actuator of the clutch to shift gears by combining a transmission ratio of the transmission device with a transmission ratio to obtain a corresponding gear of the automatic manual transmission; the automatic manual transmission is characterized in that the clutch is arranged downstream of the secondary shaft of the gearbox.