The DLR-Navteq importer reads Navteq's GDF databases converted using Elmar's tools. The importer reads unsplitted network versions. The option for reading them is --dlr-navteq-prefix <FILE> or --dlr-navteq <FILE> for short. Please note that the prefix must be given only, example:
netconvert --dlr-navteq=berlin_ --output-file=MySUMOFile.net.xml