A material transfer vehicle for transferring asphalt material from a supply truck to an asphalt paving machine, said vehicle comprising: (a) a truck-receiving hopper (25;42) that is adapted to receive asphalt material from the truck; (b) a truck-unloading conveyor that is adapted to receive asphalt material from the truck-receiving hopper (25;42), said truck-unloading conveyor having an entry end that includes a hopper opening adjacent to the truck-receiving hopper (25;42); (c) the truck-unloading conveyor including a hydraulic drive system and an engine that provides power for the drive system; (d) a system for controlling the flow of asphalt material from the truck-receiving hopper (25;42) into the entry end of the truck-unloading conveyor in order to optimize at least one operating parameter, said system comprising: (i) a baffle that is mounted on the truck-receiving hopper (25;42) adjacent to the entry end of the truck-unloading conveyor; (ii) a controller that is connected to the baffle and adapted to cause the baffle to increase or decrease the hopper opening into the truck-unloading conveyor to automatically control the size of the hopper opening based on the at least one operating parameter; (iii) a sensor for detecting the at least one operating parameter, said sensor being connected to the controller so that changes in the at least one operating parameter can be communicated to the controller; wherein the controller is adapted to control the flow rate of asphalt material into the hopper opening of the truck-unloading conveyor in order to optimize the at least one vehicle operating parameter; characterized in that: the at least one operating parameter is a parameter of the material transfer vehicle and comprises hydraulic pressure in the hydraulic drive system of the truck-unloading conveyor and/or speed of the engine that provides power for the drive system of the truck-unloading conveyor. (a) a truck-receiving hopper (25;42) that is adapted to receive asphalt material from the truck; (b) a truck-unloading conveyor that is adapted to receive asphalt material from the truck-receiving hopper (25;42), said truck-unloading conveyor having an entry end that includes a hopper opening adjacent to the truck-receiving hopper (25;42); (c) the truck-unloading conveyor including a hydraulic drive system and an engine that provides power for the drive system; (d) a system for controlling the flow of asphalt material from the truck-receiving hopper (25;42) into the entry end of the truck-unloading conveyor in order to optimize at least one operating parameter, said system comprising: (i) a baffle that is mounted on the truck-receiving hopper (25;42) adjacent to the entry end of the truck-unloading conveyor; (ii) a controller that is connected to the baffle and adapted to cause the baffle to increase or decrease the hopper opening into the truck-unloading conveyor to automatically control the size of the hopper opening based on the at least one operating parameter; (iii) a sensor for detecting the at least one operating parameter, said sensor being connected to the controller so that changes in the at least one operating parameter can be communicated to the controller; (i) a baffle that is mounted on the truck-receiving hopper (25;42) adjacent to the entry end of the truck-unloading conveyor; (ii) a controller that is connected to the baffle and adapted to cause the baffle to increase or decrease the hopper opening into the truck-unloading conveyor to automatically control the size of the hopper opening based on the at least one operating parameter; (iii) a sensor for detecting the at least one operating parameter, said sensor being connected to the controller so that changes in the at least one operating parameter can be communicated to the controller;