A Prufspitze is a penetrator or test pick or testing spike according to Ernst and the Griff would be the handle of the thing as far as I can figure out. When the technical inspection association/authority (TÜV or DMV) wants to check how deep the rust is on your car chassis, they poke around with a tool that looks like what Ernst describes. The problem is, Ernst's tool is neither a standard car component nor a part of the car's standard accessories/tools package, so I do not know why it would be on your list. Your author might mean something completely different.