In critical braking situations, specific criteria such as brake pressure and road speed are used to activate the adaptive brake lights if necessary. When activated, the brake lights flash to give drivers behind even better warning of the risk of a rear-end collision.

Studies have shown that drivers’ brake-activation response times are shortened by up to 0.2 seconds when emergency braking is indicated by a flashing red warning signal instead of conventional brake lights. At a speed of 80 km/h, this reduction in response time corresponds to a reduction in stopping distance of approx. 4.40 metres. The brake lights flash with a frequency of approx. 3 Hz (with bulbs) or approx. 5 Hz (with LEDs). Tests have shown this frequency to be particularly effective.

As soon as the vehicle is moving at less than 10 km/h or has come to a stop, or Brake Assist is no longer active and vehicle deceleration falls below 6.5 m/s² for 150 ms, the brake lights light continuously again.

The adaptive brake light comes on when:

The ATTENTION ASSIST function is particularly helpful on long journeys and when driving at night; the system warns the driver if it detects signs of failing attention and increasing weariness. This driving assistance system can warn the driver when it identifies typical signs of fatigue, which in turn improves handling safety.

ATTENTION ASSIST continuously analyses driving behaviour and steering movements. If the system detects certain steering patterns that frequently accompany drowsiness, it warns the driver visually by displaying the "coffee cup" symbol in the instrument cluster at the same time as emitting audible signals. ATTENTION ASSIST can be activated and deactivated in the main menu of the instrument cluster under "Assistance systems". When switched on, it is active at speeds between 80 and 180 km/h.

The bi-xenon headlamps are a further development of the familiar xenon headlamps, offering xenon technology for both low and high-beam. LEDS are used for the daytime running lamps, the indicators and the side lights.

The light source is a gas-discharge lamp in which an arc is generated in a quartz cylinder containing a mixture of gases. A single gas-discharge lamp is used for both the main and the low beam for each headlamp. The entire beam is used for the main-beam setting. When switching to the low-beam setting, a shutter is inserted between the lamp and the lens, blocking out the portion of the beam directed into the distance.

The tail lights, indicator lamp and licence plate lamp also use LEDs (the brake lamp, reversing lamp and rear fog lamps use conventional bulbs).

In critical situations, the Electronic Stability Program ESP® can help to stabilise the vehicle by applying a braking force to individual wheels and by adjusting engine performance.

If the ESP® system detects a critical situation, it applies the brakes systematically to one or more wheels according to the situation. Should the system consider it necessary, it will also make an automatic adjustment to engine torque. In this way ESP® helps the driver to stabilise the vehicle within the laws of physics – particularly when cornering and during sudden evasive manoeuvres.

The Intelligent Light System – as an active component of the safety concept – ensures the best possible visibility in all weather conditions and the most diverse traffic situations. When encountering oncoming traffic, in curves, fog or on free stretches of road the system adjusts to the situation adapting the characteristics of the light individually.

Too small of a gap between vehicles is the main cause of severe accidents. The newly developed radar-based collision warning system COLLISION PREVENTION ASSIST can improve safety and ride comfort by warning drivers when the gap to preceding vehicles is too small and can support the driver’s braking when it detects danger.

The new B-Class is the first Mercedes-Benz in its segment which uses a radar-based collision warning system. The system can detect gaps that are too small between the vehicle and objects in front driving at speeds of over 30 km/h. If the system detects the danger of a rear-end collision and a possible impact, the driver can be warned visually and audibly.

If the system detects a danger and the driver brakes at the same time, the adaptive Brake Assist can intervene: it provides the driver with the exact degree of braking power needed to ideally avoid an imminent collision. The COLLISION PREVENTION ASSIST is an innovative component of the integral safety concept from Mercedes-Benz.

Lane Keeping Assist warns the driver if the vehicle begins to leave its lane unintentionally. A series of three vibrations of the steering wheel, imperceptible to the other vehicle occupants, serves as the warning signal. The system can recognise manoeuvres during which drivers leave their lane intentionally - when cutting a corner, for example - and thus does not issue a warning unnecessarily.

The Blind Spot Assist can detect vehicles in the blind spot and give the driver a visual warning in the form of a red triangle in the exterior mirror. Should the driver nevertheless activate the indicator, despite this visual warning, an audible warning is also triggered. The system is active from speeds of 30 to 250 kilometres per hour. Under 30 kilometres per hour a yellow triangle indicates that the system is inactive.

The anti-lock braking system (ABS) enhances driving safety, especially when braking for hazards. During hard braking the anti-lock braking system reduces wheel lock-up by modulating the braking pressure of the individual wheels.
This ensures that the vehicle remains directionally stable and steerable while maintaining maximum braking power.
In other words: ABS allows the driver to brake and steer simultaneously – allowing precise evasive manoeuvring – in order to avoid an accident.

The acceleration skid control (ASR) ensures that the wheels do not spin when accelerating. Especially when moving off on snow, ice and loose chippings, the acceleration skid control prevents individual wheels from spinning and the vehicle from sliding out to the side.

The system uses speed sensors to monitor the slip characteristics of the wheels. If the system senses a wheel is starting to spin, the acceleration skid control corrects the wheel speed by braking and intervening in the engine management system, thus reducing the wheel slip and wheel spin.

Brake Assist can detect emergency braking situations based on the speed with which the brake pedal is depressed and assists the driver by increasing the brake pressure. The system interprets a certain speed at which the accelerator pedal is released and the brake pedal depressed as an emergency situation, and automatically builds up maximum braking power within a few fractions of a second.

Brake Assist is integrated in the Electronic Stability Program ESP® and employs the latter’s technology to control brake pressure. No additional components are therefore required. A sensor permanently monitors the speed at which the brake pedal is depressed and transmits this data to the electronic control unit.

If an unusually high pedal speed is registered, the system concludes that there is an emergency braking situation. The system then helps the driver to perform an emergency stop by automatically increasing brake pressure in the wheel brake cylinders. ABS continues to precisely meter the braking power up to the slip threshold, which ensures that steering control is maintained. Once the driver releases the brake pedal, automatic brake boosting ceases immediately.

When the PRE-SAFE® system detects the typical risks of an accident, it can activate preventive safety systems depending on the driving situation and vehicle equipment. These can help to reduce the risk of injury to the vehicle occupants.

The PRE-SAFE® system is able to recognise an impending accident because it represents a synergy of active and passive safety features unique to its vehicle class: it systematically accesses the sensors of existing systems such as ESP® and BAS, which are able to detect typical critical driving situations and provide the appropriate information to the PRE-SAFE® system, which thus supplements the safety systems fitted as standard.

Examples include securing of the driver and front passenger in their seats at an early stage by electric belt tensioners to prevent undesirable body movements and almost complete closure of the side windows and sliding sunroof to protect occupants from any objects entering the vehicle.

The airbags for the driver and front passenger provide protection for the occupants’ upper torso in a collision, and also afford additional stability to the entire body. They are thus able to mitigate the severity of injuries sustained in an accident. If the crash sensors detect a corresponding collision, the airbag is deployed. For this, a current impulse is sent from the control unit which ignites the kneebag’s initiator, which in turn ignites a solid propellant. The gases which are released in this way fill the airbag. The gases are subsequently expelled from the side of the airbag, away from the occupants.

The gas generators of both airbags work in two stages. Both stages are activated depending on the braking force applied. Depending on the predicted severity of the impact, the first stage of the gas generator is initially activated and the airbag only partially filled (60% for driver and 70% for front passenger). If a higher severity of impact is predicted, the second stage of the gas generator is activated after a slight delay and the airbag is completely filled.

The ISOFIX child seat attachment system is a quick, convenient, non-vehicle-specific system conforming to ISO standards. It allows quick and easy child seat attachment in the rear. Its fixed anchorage points ensure a high degree of protection in the event of an accident.

A special ISOFIX child seat engages in the attachment points housed in the lower area of the backrest. This creates a rigid connection with the vehicle structure, meaning that seat movements caused by slack or incorrectly fitted seat belts can be avoided. TopTether is an additional safeguard that is attached at a point behind the rear head restraints. It further reduces the risk of the child seat tilting forwards in the event of a crash.

The kneebag on the driver’s side helps to protect the legs during impact and also stabilises the entire body. It can thus help mitigate the severity of injuries sustained in an accident. If the crash sensors detect an accident, the kneebag is deployed.

For this, a current impulse is sent from the control unit which ignites the kneebag’s initiator, which in turn ignites a solid propellant. The gases which are released in this way fill the kneebag. The gases are subsequently expelled from the side of the kneebag, away from the occupants.

The pelvisbags for the driver and front passenger provide protection for the pelvic region and hip in a collision. They are thus able to mitigate the severity of injuries sustained in an accident. If the crash sensors detect a relevant side collision, the pelvisbag is deployed.

The pelvisbag is deployed in the space between the front-seat occupants’ pelvic region and the door panelling. The pelvisbag then braces itself against the impact area, pushing the occupant’s pelvic region away from the door panelling at a very early stage of the collision.

The sidebags in the rear are stored behind the wheel arch lining. When they are deployed during a side collision they provide potential protection for the chest area of the rear-seat passengers.

They are triggered when the central control unit and the side satellite sensors register acceleration or deceleration forces acting on the vehicle in excess of a certain threshold. The sidebags deploy at chest height between the vehicle side and the occupant.

In the event of a sufficiently severe side impact, the windowbag deploys to cover the side windows and reduce the risk of a collision between the passenger’s head and the side of the vehicle or of objects penetrating the vehicle interior. The windowbag is triggered simultaneously with the pelvisbags and always on the side of the vehicle involved in the side impact.

When activated, the windowbag spreads across the side windows between the A-pillar and C-pillar to form a curtain approx. 300 mm in height and approx. 120 mm thick. The windowbag covers a large part of the surface area at the side when deployed.

The windowbag provides the following advantages:

After an accident the interior lighting switches on automatically and helps the occupants to find their way around the vehicle.