Active Cruise Control with Stop & Go function - or ACC Stop&Go for short - not only maintains the desired distance to the vehicle in front, in heavy traffic it also slows the car to a standstill. Active Cruise Control with Stop & Go function is a further development of the familiar Active Cruise Control (ACC) system. At speeds between 30 and 180 km/h (19 - 112 mph), it enables drivers to cruise along comfortably in free-flowing traffic on motorways or country roads at their preselected speed and while maintaining their desired distance to the vehicle in front. If traffic conditions demand, the system also adjusts the car's distance automatically to the vehicle ahead of it.

ACC Stop&Go likewise relieves the workload on the driver of the new BMW 3-Series Sedan in slow-moving traffic and tailbacks. In stop-start conditions the car is braked to a standstill, if required, and pulls away again automatically. This allows the driver to move comfortably with the flow of the traffic and delegate the job of creeping, stopping and moving off to the car. If the car has been at a standstill for a longer period of time (more than three seconds), the driver has to give the command for the car to automatically pull away again by nudging the accelerator or pressing the "Resume" button on the multifunction steering wheel. The driver can adjust the car's speed at any time while the system is activated by pressing the accelerator or brake pedal, and so retains ultimate responsibility for the car at all times.

The maximum deceleration applied by Active Cruise Control with Stop & Go function at low speeds is 4 m/s2 (13 ft/s2). At higher speeds, it is limited to a comfortable 2.5 m/s2 (8 ft/s2). If the driver needs to intervene because the vehicle in front is braking extremely heavily, he is prompted to do so by visual and acoustic signals. At the same time, the deployment thresholds of the Brake Assistant are lowered and the Brake Standby function of the DSC system is activated.

Active Cruise Control with Stop & Go function works using a latest-generation radar sensor. The "full-range" radar can detect vehicles travelling up to 200 metres (656 ft.) in front of the car in virtually any weather conditions. This innovative sensor is integrated discreetly into the front apron of the car and needs no individual adjustment. The system's measuring beam is sufficiently broad at distances up to some 60 metres (approx. 200 ft.) from the car that vehicles in the adjacent lanes can be detected by the radar sensors - within certain limits - earlier than with the conventional ACC system. If another vehicle moves into the same lane as the driver's car, Active Cruise Control with Stop & Go function adapts the speed of the BMW 3-Series precisely to that of the vehicle moving over.