How exactly does the “Hill Descent Control” work? / HDC button

More and more SUVs have a so-called hill descent assist or one hill descent assistant standard on board. her too Hill Descent Control (HDC) This function ensures that a (slippery) slope can be driven down safely without losing traction.

This is exactly how the hill descent assistant works

The HDC function can usually only be used with low speeds (max. 30 km/h) activate. On vehicles with a driving mode selector switch, it is also often activated automatically when you switch to “Offroad” mode. For example with the Seat Ateca or the VW Touareg. If the assistant is active (this is usually displayed again in the speedometer or the button lights up), the rest is very simple: If you are standing at the beginning of a mountain, just let go of the brake completely. The vehicle then controls the descent completely. You just have to steer. The hill descent assistant now ensures that you can, for example, drive down an icy or muddy slope safely without one of the wheels locking. So the wheels are all spinning, maintaining traction.

HDC active (here in an Audi A4)

Wheels do not lock, the vehicle stays on track

If you were to climb a steep incline, e.g. an icy road, drive down with the brake pressed, wheels would always lock and you would quickly lose track or even spin – or shoot down the hill with loss of control. The hill descent assistant optimally distributes the braking force and also ensures that more braking force than usual is also given to the rear wheels. So it can definitely go downhill better than you could do it manually. The help of the HDC can be heard in noises from the brake booster (such as ESP intervention). On vehicles with a manual transmission, it is best to shift into first gear and completely release the clutch and brake.

In our video we show how the Hill Descent Control at the Seat / Cupra Ateca on a steep, icy slope. Even here, the vehicle remains steerable, but due to the very slippery slope, we also gain speed here: