Iphone map apps quit working in one car

We just bought a new vehicle. Both my husband's and my iphone map apps go completely haywire when we are driving in it. They work fine in both of our other vehicles, one of which has Car Play and the other does not.

Both phones and all map apps also work fine when we get into the new vehicle with the map apps on -- but the vehicle turned off. As soon as we turn on the new vehicle, which came with Car Play installed, all of the the maps instantly reorient and tell us that we're miles away from our actual location. That happens both with the iphone that is connected through Car Play when the car is started, and the iphone that is NOT connected through Car Play at that moment. When driving, map apps will tell us to turn left on Road X, when we're driving down a freeway, or they will suddenly tell us we're in a an entirely different state.

Something in the new vehicle or with its version of Car Play clearly is interfering with the GPS systems on our iphones, whether or not they are connected. But we basically lose all GPS functions through our phones.

I've read of other people having similar problems. Does anyone have any suggestions?