Before a product is approved by Mercedes-Benz and can carry the Mercedes-Benz Genuine Accessory seal of approval, it must first pass a series of extremely demanding internal tests. The strict quality and safety standards of the premium manufacturer go well beyond all legal requirements. The rigorous schedule includes crash tests, shake tests, emergency braking at different speeds and sudden changes of lane. There are also strenuous endurance runs, simulating the life of a car in time compression, and also salt spray tests and climate chamber testing. The programme is rounded off with aerodynamic and acoustic measurements. The test requirements are well in excess of what a Mercedes-Benz customer would experience under normal driving conditions.
No compromises with safety-related assemblies
The gruelling quality tests can last up to four months before a new product is approved as a “Genuine Mercedes-Benz Accessory”. Testing of safety-related assemblies, such as carrier systems or roof boxes, is especially demanding.
As a rule, the development, design and testing of accessories is generally aligned towards the model or component it will be used with. Roof racks, for example, are always tested with the type of Mercedes-Benz model on which they are to be mounted. This is done to ensure that the boxes conform precisely to specific aspects such as roof geometry, vehicle dimensions or the intended use of the particular model series. The procedure also helps ensure that the accessory does not damage the vehicle in any way.
Extreme stress loads on the vibration table
Some of the most spectacular tests are those carried out on the vehicle body test rig, also known as the vibration table. Here, the roof and the carrier are shaken back and forth and up and down with such a level of violence that most casual observers are left feeling dizzy. Despite the exceptionally high forces that are brought to bear on the carrier, a bicycle or anything attached to it must not fall down, become loose, or damage any other part of the vehicle. An accessory may feature the Mercedes-Benz star only after it has passed this stringent test and withstood the extreme loads it has been subjected to.
Tests tougher than the “City-Crash”
The internal crash tests at Mercedes-Benz are conducted at higher speeds and acceleration rates than those required by the DIN 75-302 (German Institute for Standardisation) or ISO 11154 (International Standard Organisation) standards, or also the “City-Crash”. Although not required by law, the latter test is recommended by the German consumer watchdog organisation Stiftung Warentest, and by the German Automobile Association (ADAC). The test is meant to simulate a typical rear-end collision at a moderate speed in an urban setting.
A roof rack’s life examined in time compression
Laboratory examinations are supplemented with extensive driving tests on Mercedes-Benz test tracks and in situations based on real-life traffic. One such test is the special driving endurance test over a distance of 25,000 kilometres with a 50-percent roof rack overload. The route here includes fast stretches of motorway, together with winding secondary and rural roads. There are also several hundred kilometres of testing over rough road surfaces.
Additional tests are conducted for handling, emergency braking manoeuvres at various speeds and for driving dynamics, such as the ISO evasion test. The programme is rounded off by high-speed drives and extended trips on rough road test circuits.
Optimised aerodynamics means lower fuel consumption
A key aspect of accessory development involves optimising aerodynamic and acoustic properties. The roof racks and boxes are put through an extensive testing programme in a wind tunnel, where they are placed at different angles to the wind and driven at various speeds, up to the maximum speed of the Mercedes-Benz model in question. A predefined internal benchmark serves as the target value that a new product must achieve. Customers benefit from the resulting improvements in aerodynamics in the form of significantly lower fuel consumption than would be possible with a comparable non-genuine accessory.
Acoustic properties are then tested and optimised on the road; the goal here is to eliminate any unpleasant noises such as whirring and whistling. In many cases, these can be identified only when the accessory is driven with the vehicle it is to be used with, which is also why each rack is approved only for specific model series.
Corrosion tests that go far beyond the norm
Great efforts are also made to ensure the long-term quality that is the hallmark of every Mercedes-Benz product. For example, the corrosion tests conducted on individual components in saltwater sprayers last more than twice as long as the time stipulated in the DIN 75-302 standard. In addition, the products are put through extended corrosion tests while mounted on the vehicle, and are also exposed to extreme temperatures in a climate chamber. All of these tests are meant to ensure that the racks will not develop hairline cracks in freezing temperatures or deform in extreme heat.
Design: perfect alignment with the vehicle silhouette
Mercedes-Benz applies the strictest criteria to design, which is why genuine accessories are developed in close cooperation with design engineers for the vehicle models at the Sindelfingen Design Center. The roof boxes and roof rack systems thus blend in harmoniously with the design lines of the Mercedes-Benz passenger cars, combining maximum functionality with supreme elegance.