BMW’s Active Steering system uses a clever planetary gearbox on the steering shaft that is computer controlled to vary how quickly the front wheels respond to steering-wheel input. That means the car can offer light, quick steering at low speeds, while maintain a firm and slow ratio for better high-speed stability.
“At moderate speeds, a quick steering ratio is desirable to keep form banging elbows or shuffling the wheel hand-to-hand around a 90-degree corner. The problem is that ultrafast ratios make the car twitchy when you’re cruising 10 mph over the limit. Sneeze, and you’re in the ditch. The solution to the dilemma is called Active Steering, an integral part of the 2004 BMW 5-series Sport package.” — DS