I would think your sat nav is on the Hard Disc Drive. I understood all navs after late 09 were HDD type not dvd. If it's HDD it is updated by using a USB drive. This can only be done by Lexus. Personally, I'd do this every 4 yrs or so. I've just done mine from 2010 version to 2014 version. Think they come out every April. So, you might be wise to wait until late April to get the 2015 version.