Brake Assist
This system, developed by Mercedes-Benz to shorten emergency stopping distances, takes over if a driver is too hesitant or gentle in applying the brake pedal in a critical situation. The system automatically develops maximum brake boost with split-second speed, so reducing the stopping distance significantly. Tests provide impressive proof of the effectiveness of Brake Assist: on a dry road, most drivers need up to 73 metres for an emergency stop at 100 km/h, since they apply the brakes too gently. With Brake Assist, the car can be brought to a standstill after just 40 metres, a reduction of 45 per cent.
Common-rail injection
With the state-of-the-art common-rail direct fuel injection used in the diesel models, Mercedes-Benz has achieved an ideal compromise between economy, torque, ride comfort and long life. Whereas conventional direct-injection diesel engines must repeatedly generate fuel pressure for each injection, in the A-Class CDI engines the pressure is built up independently of the injection sequence and remains permanently available in the fuel line. The common rail upstream of the cylinders acts as an accumulator, distributing the fuel to the injectors at a constant pressure of up to 1350 bar. Here high-speed solenoid valves, regulated by the electronic engine management, separately control the injection timing and the amount of fuel injected for each cylinder as a function of the cylinder's actual need. In other words, pressure generation and fuel injection are independent of each other. This is an important advantage of common-rail injection over conventional fuel injection systems. The CDI diesel engines offer flexibility in controlling both the main injections and the pilot injections: a few milliseconds before the main fuel injection occurs, a small pilot charge of fuel flows into the cylinder. This ignites immediately, thereby preheating the combustion chamber. As a result, better conditions are created for the main injection process, which has a favourable effect on noise.
Dynamic route guidance
If dynamic route guidance is specified, the "MB Audio 30 APS" radio (optional) uses the car phone to contact the traffic telematics service provider Tegaron Telematics. Tegaron Telematics analyses the information from Gesellschaft für Verkehrsdaten, a traffic data provider that monitors the traffic situation on German autobahns by means of some 3,800 infrared or ultrasonic sensors. Using the Short Message Service (SMS) of the mobile phone network, Tegaron transmits congestion warnings at regular intervals to the dynamic navigation system of the A-Class, which is therefore able to take the latest traffic information into account and recommend an alternative route in the event of a hold-up ahead. Dynamic route guidance by mobile phone is already in operation in Germany and will soon be available in other European countries too. A second way in which the "MB Audio 30 APS" radio can receive digital traffic data for dynamic navigation is via the Radio Data System (RDS) and Traffic Message Channel (TMC). Broadcasting stations transmit inaudible signals which are decoded and evaluated by the MB Audio 30 APS radio. These signals contain information about hold-ups identified either by induction loops in the road surface of autobahns or by the police. The information contained in these messages corresponds to the regular (audible) traffic news provided by the radio stations and is free of charge. RDS-TMC is already in operation all over Europe. Dynamic route guidance with this technology is currently operational in Germany, and preparations are also under way to introduce it in other European countries.
