In the new Mercedes-Benz climate tunnel, cars are tested under extreme conditions. In the €52 million plant, they don\'t wait for the right weather – they make it themselves. The test bench of the heat tunnel features an array of 32 lamps designed to simulate the sun\'s powerful rays by generating up to 1200 watts per square metre over an area measuring 8 x 2.5 metres. In extreme cases, the tunnel can reach temperatures of up to 60 degrees Celsius – as hot as Death Valley or the Sahara. With the infinitely variable \"hot road\" function, it is even possible to reproduce the effect of warm asphalt on a summer road. The development engineers can arrange for up to 2400 litres of water per hour to pour down on a vehicle. But it\'s not just the volume of rain that can be varied - the size of the drops can also be pre-set. A simulated tropical storm can be used to check whether a car is watertight overall and whether the windscreen wipers are functioning properly. Arctic freeze. The cold tunnel can generate temperatures down to minus 40 degrees Celsius, for example, to test a vehicle\'s heating system. As soon as the thermometer drops below freezing, the facility switches to \"cold lighting\" as conventional neon lamps cannot withstand frost. At temperatures below freezing, the pre-cooled spray water turns into snow and the metal floor becomes as slippery as an ice rink. Light breeze or hurricane. The huge fan is capable of simulating winds speeds of up to 265 km/h. Even at a wind speed of 100 km/h you are no longer able to stand upright. The fan is mounted on massive steel springs to protect the facility\'s electronics from the slightest vibration. The \"weathermen\". Daimler invested €52 million in the two climate tunnels at its Sindelfingen plant. In the spring of 2011, following two years of construction work, the development engineers began using the state-of-the-art facility to test new vehicles under extreme weather conditions prior to their market launch. It is a huge advantage not to have to rely on local weather conditions. Even in the world\'s extreme climate regions it is not always possible to count on the weather, let alone the worst weather. In the climate tunnels, on the other hand, the conditions are always completely controllable: the \"weathermen\" are able to set a whole host of parameters on their monitors – from the size of the raindrops and the humidity, through to the surface temperature of the road. In six so-called conditioning chambers that resemble huge refrigerators, vehicles are prepared and prototypes adjusted to the correct starting temperature. As well as testing the heating and air-conditioning systems, the artificial weather simulator can also be used to check a wide range of vehicle components, ranging from windscreen wipers to brakes. The climate tunnels are an important intermediate stage between virtual testing of a new model on the computer and real-life road testing. It is still essential to test vehicles under actual road conditions, but climate tunnels help to reduce the number of test miles which have to be covered – and that can only be a good thing for the real climate.