In this paper the authors present a simple example of how ISO 26262 can impact the development of a simple function - Start/Stop. The examples is limited, but it is easy to understand that for larger examples and more safety critical the complexity raises. Now, imagine that one re-classifies the function or divides the ASIL levels...
The paper needs more examples and more hard-data to make the illustration better, but it contains the basics. I recommend further reading upon BeSafe - a project done by Volvo Technology in this area - http://www.kth.se/polopoly_fs/1.354272!/Menu/general/column-content/attachment/Presentation,%20Johan%20Karlsson.pdf