<P> Unexpected gear changes can affect the attitude of a vehicle in marginal conditions . </P> <P> Torque converters and CVT transmissions make changes in vehicle speed less apparent by the engine noise, as they decouple the engine speed from vehicle speed . </P> <P> Lockup torque converters that engage and disengage at certain speeds can make these speeds unstable--the transmission wastes less power above the speed at which the torque converter locks up, usually causing more power to the wheels for the same throttle input . </P> <P> Torque converters respond quickly to loss of traction (torque) by an increased speed of the driving wheels for the same engine speed . Thus, under most conditions, where the static friction is higher than the kinetic friction, the engine speed must be brought down to counteract wheelspin when it has occurred, requiring a stronger or quicker throttle reduction by the driver than with a manual transmission, making wheelspin harder to control . This is most apparent in driving conditions with much higher static friction than kinetic, such as packed hard snow (that turns to ice by friction work), or snow on top of ice . </P>

When did the first automatic car come out