sentences:  Depending on implementation, friction between drive mechanism and ground, and available power, a vehicle with differential steering may have a zero turning radius or a "curb-to-curb turning circle" equal to the length of the vehicle by driving each side at the same speed but in opposite directions.This is also called a "neutral turn".Vehicles on which only one drive wheel on each side is rigidly aligned and all others are free to caster, such as wheelchairs and wheeled robots, require the least power to turn.