Abstract: This invention concerns the transport of fluids. In particular in a first aspect it concerns a truck fitted with a tank and a fill line to the tank, comprising: An inlet in the fill line configured for connection to a hose that is, in use, connected to a fluid source to change the amount of fluid in the tank. A sensor to make measurements from which the amount of fluid in the tank can be determined. A valve to allow fluid flow through the inlet, both to increase and decrease the amount of fluid in the tank. And a data acquisition device to periodically record sensor measurements and to associate a time and place with each record. In a second aspect the invention concerns a control system for the truck. In a third aspect the invention concerns a control system for a fleet of trucks.