Mercedes-Benz has bundled its worldwide vehicle testing at the Immendingen Test and Technology Centre (PTZ). Gradients, curves and poor road surfaces on the test site, as well as those in the surrounding Black Forest offer the best conditions for optimising the chassis on the new Citan. Its driving assistance systems were also tested and fine-tuned in the Black Forest, whilst the functionality of the electrical and electronic systems were tested in Immendingen. The PTZ test centre was officially opened in September 2018 after a build time of around three and a half years. Immendingen is located in Germany's Baden‑Württemberg region, 130 kilometres south of Stuttgart and 40 kilometres north of Lake Constance.
Systematic validation of the entire vehicle serves to safeguard the high quality standards of Mercedes‑Benz. After digital calculation and testing on the test stand, the prototypes and pre-series vehicles of the new Citan underwent more than 500 individual tests in Europe. Over the course of numerous test drives, the small van was put through its paces in two winters and two summers with temperatures ranging from minus 25 °C to plus 40 °C.
The PTZ was a key station throughout the testing operations. It was developed on a former military training ground of the German army. The impressive topography with its various levels and heights ranging from 660 to 880 metres above sea level was intensively integrated into the development of the test route layout. Over a total area of 520 hectares, the PTZ test centre houses more than 30 different test and monitoring routes. There, the most varied of situations can be simulated, such as complicated traffic at junctions in inner cities, journeys on rough cobbles or driving on a mountain pass. The new acoustic test route uses a road covering which has a precisely defined friction value. Acoustic testing of the new Citan was carried out here in order to fine-tune the NVH aims.
As part of the comprehensive measures put in place by Daimler to protect nature, Daimler collaborated with nature and environmental groups. The aim was for technological advancement to be as nature-friendly as possible. Thus, on the Immendingen testing area, habitats were created for plants and animals. Some areas were reforested and planted, plus a passage for wild animals also crosses the premises.
 Above sea level: fixed altitude in relation to which altitude measurements are made