The upside of winter weather and a bit of snow is the chance to go sledging. When you do, what’s your favourite way of trying to steer out of trouble? Sit up with legs forward and gingerly dab a heel in the ground to slew yourself round? Or are you game enough to take the full-on approach, lying face down gouging left and right toes into the snow?
Either way, the effect on the sledge is similar to that as torque vectoring on a car, rotating it to make it change direction without using steering. Torque vectoring simply means directing more torque to one driving wheel or the other to make the car rotate or ‘yaw’. Doing that can help overcome power understeer or over-enthusiastic oversteer – or, in a more subtle way, simply improve agility and the car’s appetite for changing direction when you want it to. With four-wheel drive and a centre differential, torque can be vectored between front and rear axles in the same way.
Torque vectoring normally works by piggybacking on the natural properties of a differential, which allow one wheel on an axle to go faster or slower than another. Mitsubishi defined the technology with its Active Yaw Control on the Lancer Evolution IV rear axle. It controlled which rear wheel got more or less torque with an electronically controlled wet (bathed in oil) clutch pack either side of the differential gears in the rear axle. It quelled understeer by channelling more torque to the outside rear wheel and, when launching, could direct torque to the wheel with most grip. In rallying, it would help make the Mitsubishi Evos a dominant force.