Idle curiosity. The electronic unit that you put in your car or in more recent cars is inbuilt that provides you with maps and directions, usually spoken ones. What do you call it in the US?
Yes, I mostly hear it called “a GPS,” though of course that’s just part of the technology that makes it work, not what what it does. I’ve also heard it called a “navigator,” and a “directions thingy.”
Global Positioning System; it’s a GPS box. I call mine “Hal.”
“navigation” or “nav.”
I say GPS, usually.
Yep, GPS is the common term. If someone said “satnav” my first thought would be that they were talking about some kind of military thing.
If it’s built in, you say your car has GPS. If it’s a device, it’s “a GPS”, but it can also be used as an adjective. I’ve never heard satelite used at all, and navigation is only used in ads. “Buy our car with a GPS navigational system and built in On-Star, and never get lost again!”
GPS back home in the states.
Navi here in Germany.
I only know satnav from British media. It does always sound vaguely military to me.
My 4 1/2 year old grandson calls it “The lady”. But no I had never heard satnav until I read this thread.
Same here, I heard it by listening to BBC Radio podcasts. And I agree with BigT’s grammar distinctions: Cars can come with GPS built in. Your phone has GPS. You can buy a GPS/a GPS unit to put in your car.
Yes, GPS or “the GPS”. It’s even become something of a verb - “Where do I turn?” “I dunno, GPS it.”
Although in our family, it’s known as “the Bitch”, 'cause she gets a little cranky when she has to recalculate because we’ve missed a turn. 
Geocachers frequently refer to the handheld kind as a “GPSr”.
I’d say yes, it’s typically called GPS in the US, although GPS is the technology used by the device, not the device itself. The vehicle nav units can’t even give you coordinates or do other things I’d consider basic to a real GPS unit. Their interface is dedicated only to navigation.
Many cars have buttons for them labeled as “SAT”, “SATELLITE”, “NAV” or “NAVIGATION” and say something about navigation on the splash screen. Many (all?) have disclaimers about using navigation while driving when they first start. Some probably have “GPS” buttons too, but I’d wager the car manufacturers use some variation of satnav more often that GPS.
Which stands for GPS receiver.
The irony here being that GPS is, in fact, the US military satnav system. They’re nice and let the civilians use it, too.
GPS. If I heard somebody talking about a satnav, I would assume they were talking about the satellites that broadcast the signals that GPS’s receive.
At least in the north American market, “SAT” buttons almost certainly refer to satellite radio (Sirius/XM.)
Navi is a brand of GPS’s in the United States but it isn’t a generic term for them.
I call it “The Lady” also.
“The Lady says turn left, so I’m turnin’ left, godammit!”