Apple Maps and car bluetooth

I am using an iPhone XR and running the latest iOS. When my phone is connected via bluetooth to my car and I am using Maps, I no longer have the option to choose between hearing turn-by-turn directions through my car's stereo system OR via the speaker on my phone; rather, directions are ONLY heard through my car's stereo. Due to the fact that my car's stereo and Apple Maps' turn-by-turn directions don't play well together, I want the option to hear my directions via my phone's speaker and NOT via my car's speakers. BUT I also want to have my phone remain connected via bluetooth for hands-free phone calls, etc. No matter where I look, I cannot figure out how to set my iPhone controls to make this happen. Any helpful suggestions would be greatly appreciated.