Other than a number of exceptions, BMW works by using power-assisted rack-and-pinion steering on each individual model. In concept, contemporary BMWs are no different compared to the power steering methods from 40 years back - turning the steering wheel rotates a shaft, which slides a toothed rack with aid from https://automotivenews62369.bloguetechno.com/types-of-power-steering-fluid-for-bmw-fundamentals-explained-62754290