Extreme tests at sub-zero temperatures
Sub-zero temperatures down to -40°C, metre-high snow lining both sides of the road, snow often on the road too, coupled with just a few hours of daylight – the winters in northern Sweden are bleak and harsh. The perfect conditions to put the new Mercedes-Benz Citan to the test.
Mercedes-Benz Vans has been testing every new model under extreme conditions near to the Arctic Circle for decades. Sprinter and Vito vans have undergone rigorous winter testing on numerous occasions. Now the new Citan has followed in their footsteps.
Own test centre near the Arctic Circle
In the small town of Arjeplog, Mercedes-Benz has set up its own test centre with workshops, offices and test tracks. It is hermetically sealed to keep out prying eyes. Here and on other test tracks on a nearby lake, on a challenging mountain route, as well as driving on public roads, the new Citan urban delivery van has had to prove its mettle.
Tests focusing on cold start behaviour, the heating and ventilation, the seat heating and windscreen defrosting are par for the course in the Scandinavian winter. But testing in the Artic Circle also looks at how materials respond to extreme temperatures: how do the door seals perform, for instance? At sub-zero temperatures even plastics will go brittle and can break or tear. In certain circumstances, creaking noises may occur where materials overlap.
Such shortcomings are unacceptable for a Mercedes-Benz. If the high-quality hallmark interior of the Mercedes-Benz Citan can withstand this environment, it will take even the harshest Central European winter in its stride. The Citan has passed all the tests. As a genuine Mercedes-Benz it can now stand up masterfully to even the harshest icy-cold temperatures.
Fine-tuned suspension control systems
The Scandinavian test centre with its ice-covered terrain is also the ideal place to test and fine-tune the suspension control systems. ESP® comes as standard on board the Citan, just as it does on any Mercedes-Benz. Yet ESP® is just the overarching term for a wide array of control systems, including subfunctions such as anti-lock braking system, acceleration skid control, drive and braking torque control, engine friction torque control, understeer control, rolling-moment intervention.
Each of these systems needs to interact perfectly in a Mercedes-Benz van under the most difficult conditions and different vehicle loads, and hence the need for exhaustive testing. Measuring devices and a laptop are a constant feature on board the camouflaged test vehicles. But the finesse of the experienced developers is at least just as valuable.
Punishing itinerary at the company's own test facility
The company's own test facility in Arjeplog provides the full range of punishing terrain for testing the new Citan, including roads with a 10, 15 and 20-percent incline. Covered on one side with high-grip heated asphalt, and slick ice on the other. The engineers talk in terms of µ‑split, the different friction coefficients on the left and right. Even under these conditions, a Citan has to navigate the inclines and descents safely, just like any other Mercedes-Benz van.
Other courses with compacted snow or the long braking area with a high-grip surface on one side for high-speed braking tests push the new urban delivery van to the limit. Mercedes-Benz has precisely specified the maximum steering correction, as well as yaw-rate characteristics – rotation around the vertical axis –, including response over time and peak value. A Citan must respond safely and predictably at all times.
Icemakers prepare courses on frozen lakes
On the nearby frozen lake, local professionals – the icemakers – have prepared precisely defined courses for Mercedes-Benz, including a circuit with a diameter of 500 metres, covered with snow on the outside, roughed-up ice in the middle, slick polished ice towards the inside. Here and on the various handling circuits with their sweeping and tight bends the Citan has to demonstrate grip and handling stability. The brand's hallmark tuning of the suspension and control systems becomes apparent even at low speeds on ice.
Green light for series production
To find out for themselves about the results of this year's winter testing programme, senior management from Mercedes-Benz Vans made the journey to the far north of Sweden, among them Volker Mornhinweg. The Head of Mercedes-Benz Vans was there not only to discuss the test results and the ensuing fine-tuning measures with the development engineers.
Volker Mornhinweg also got involved in some testing himself. Two days spent in icy-cold Arjeplog behind the wheel of the Citan, putting materials and vehicle to the test. And he is impressed: "Our new suspension and our control systems are now perfectly tuned. It's something you notice on the various handling courses and when moving off or braking. I'm also extremely happy with the changes in the interior – both in terms of the heating, ventilation and air conditioning, as well as the robust materials selection. The Citan is now a bona fide Mercedes-Benz after all the tests and work our development engineers have done. And so it's ready for series production."
Credits: Daimler AG
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