Others have written there's no SD card in the 2018 nav head. Well there has to be some flash memory and an SD card is the easy way to do that. Maybe it just isn't user accessible. There's a doohickey in the compartment with aux & USB sockets that looks like it pops out with a special quarter turn wrench to expose something just the right size for a micro sd. If that's not it, does anyone know what it is? Or know for certain there really is no sd card in the system, so how do map updates go in? These pictures appear upside down.