A hybrid electric vehicle includes an engine for driving, a motor for driving, a power storage device that is configured to exchange power with the motor, and a controller that is programmed to control the engine and motor to travel with the engine running in towing mode. The controller is programmed to permit the towing mode when the towing mode is indicated and a state of charge of the power storage device is higher than a threshold value, and the controller is programmed to prohibit the towing mode when the towing mode is indicated and the state of charge is lower than or equal to the threshold value.

A system is operable for controlling a force applied on a trailer being towed by a vehicle is described to a desired force Fd. The trailer has brakes and an optional motor for providing a propelling force to the trailer. A force sensor senses fore-aft forces between the vehicle and trailer at all times while the trailer is being towed. A controller receives signals from the force sensor and is operatively connected to the trailer brakes and the motor. The system controls the force between a towing vehicle and a trailer to the desired force Fd, by any one of: (a) operating the brakes to apply a braking force to the trailer; (b) activating the motor to apply a propelling force to the trailer; and (c) operating the brakes and activating the motor to apply both a braking and a propelling force to the trailer.

A computer-implemented method of determining a torque limit for an operating state of a first vehicle combination is provided. The method includes simulating a plurality of operating states for one or more second vehicle combinations. Each operating state is based on one or more operational parameters related to physical properties of the one or more second vehicle combinations, one or more parameters related to an operating environment of the one or more second vehicle combinations, and one or more parameters related to a driving scenario of the one or more second vehicle combinations. The method includes classifying each of the simulated operating states as safe or unsafe, receiving an unsimulated operating state for the first vehicle combination, and determining a torque limit for the unsimulated operating state based on the simulated operating states.

A method of controlling a vehicle combination, the vehicle combination comprising a first vehicle unit, a second vehicle unit and an articulated coupling connecting the first and second vehicle units to each other, the method comprising determining a coupling force parameter of the articulated coupling based on a combination of motion related parameters obtained from the first and second vehicle units; selecting an operational envelope for the vehicle combination based on the coupling force parameter; and controlling the vehicle combination to operate within the operational envelope.