Abstract: A vehicle powertrain torque control provides an engine drag control mode of operation during periods of undesired engine drag induced wheel slip by modifying the torque of the vehicle engine in closed loop control to maintain a driven wheel speed at a predetermined target velocity lower than the vehicle speed by a target velocity difference providing as much engine braking as is consistent with a desired degree of lateral traction. The control derives a velocity error as the difference between the driven wheel speed and the target velocity and derives and delivers to the powertrain a torque command for reducing the velocity error. The torque control determines the engine drag control mode in response to the wheel speed sensors, preferably causing entry of the engine drag control mode when the driven wheel speed that is closest to the vehicle speed falls below the target velocity while powertrain delivered torque and throttle position are below predetermined values indicative of deceleration.

Abstract: A motor vehicle mounted system is responsive to sensed or estimated vehicle lateral acceleration and vehicle speed for detecting and signaling when the vehicle is operating on a racetrack. The system determines whether the vehicle is in a high lateral acceleration state or a low lateral acceleration state and when the vehicle is maintaining a minimum speed. The system increments a count when the vehicle is in the high lateral acceleration state if the vehicle has maintained the minimum speed for a first time since the last increment or decrement of the count and decrements the count when the vehicle is in the low lateral acceleration state if the vehicle has maintained the minimum speed for a second time since the last increment or decrement of the count. The system detects and signals operation on a racetrack while the count exceeds a predetermined threshold count and otherwise detects and signals no operation on a racetrack.