It's not useful to the story at all, and regularly I get the idea that some stunts are just done for the mere fun of it. Truckloads of cars are scrapped in various action scenes. 'Alarm für Cobra 11 - Die Autobahnpolizei' is a typical German 'krimi' (whodunnit), with a bit more action involved. It's still one of the best stunts I've ever seen. One of the first episodes of Cobra 11 I can reminisce, featured a police car hitting an anchor hanging down a bridge over the Autobahn.