Test engineer Berthold Merkle and technician Bernd Gutmann climb aboard the Setra ComfortClass S 511 HD for a test drive. At first glance the vehicle appears to be already full with passengers. Taking a closer look behind, however, you can see that water-filled dummies are simulating the travellers here. Instead of the usual suitcases, bags of sand are placed in the vehicle’s belly – with good reason, as Bernd Gutmann explains: “The shock absorbers have to cushion the load, which is why we do our tests with different vehicle loads, in other words empty, partly and fully loaded. When it comes to road conditions, we look for characteristic routes for the purpose of the vehicle in order to also test the worst case, for example cobblestones or motorways with offset flagstones.” For these measurements, the “bumometer” is used. The special sensitivity in the gluteal muscles which decides on the right shock absorbers.