Can I connect my iPad mini wifi only to my cars built-gps through bluetooth?

The is the forum for the desktop Mac Mini computer. I requested that your post be moved to the iPad forum.

Yes you can connect the iPad to the car's GPS if there is an app that supports it.

That's more a question for your GPS manufacturer. And whether or not there is an App that can talk to it, or if one is even needed.

Since we know nothing of your car or its GPS, your best course of action is to conatct your car or GPS manufacturer and read its user guide.