Does Android Auto use the GPS in my truck or the GPS on my phone?

[Android Central Question]

I am having an issue when I plug my phone into the vehicle and put in an destination, Google maps navigates from Nova Scotia to my destination. I am in NH. When I unplug the phone from the truck, my phone recalculates my trip from my current location in NH. Another tid bit of info, the truck is originally from Nova scotia. That is where it was bought.

 

[VidJunky]

I'm going to assume that the truck has its own GPS system. I'm really struggling to see how it would assume a location where it isn't since a purchase location would not necessarily be the home of the vehicle and then what to do you do if you're on a trip...? It seems odd but the only thing I can think of would be to go through the truck settings and see if there is still a home or work location saved in there from a previous owner. I wouldn't have expected it to use the truck GPS either but maybe it's an energy savings thing if the phone doesn't have to use its own.