Iš BMW troikės manualo:

Hills
To prevent overheating and the resulting
reduced efficiency of the brake system,
drive long or steep downhill gradients in the
gear in which the least braking is required. Even
light but consistent pedal pressure can lead to
high temperatures, brake wear and possibly
even brake failure.<
You can increase the engine's braking effect by
shifting down, all the way to first gear if neces-
sary. This strategy helps you avoid placing
excessive loads on the brake system. Down-
shifting in manual mode of the automatic trans-
mission, refer to page 52.