Hi NCDad,
Since you've noticed this when your iPhone is connected to two different cars, restart your iPhone. Although simple, this step can help correct some unexpected issues. It's also a good idea to make sure your iPhone is running the latest iOS version, since updates often include fixes. Updating can also help with overall performance: Update your iPhone or iPad. If an update is available, be sure to create a backup before installing it.
If the issue persists, the guidance in this resource may be helpful: If you need help with CarPlay.
Make sure that your iPhone has the latest version of iOS. If your iPhone is updated to the latest version of iOS, follow these steps — checking CarPlay after each step:
1. Check your connection to your CarPlay stereo:
• If you have a wired connection, try connecting again with a different USB cable to a different USB port if you have one.
• If you have a wireless connection, make sure that Wi-Fi and Bluetooth are enabled under Settings > Wi-Fi and Settings > Bluetooth.
2. If CarPlay doesn't activate automatically, look for the CarPlay logo on your car's display.
3. Restart your iPhone and your car.
4. Make sure that Siri is on.
5. If your iPhone isn't detected by CarPlay, make sure that CarPlay isn't restricted. Go to Settings > Screen Time > Content & Privacy Restrictions, tap Allowed Apps and make sure that CarPlay is enabled.
6. Go to Settings > General > CarPlay, tap your car, then tap Forget This Car. Then set up CarPlay again.
7. Make sure that your CarPlay stereo is using the latest firmware from the car manufacturer. Check your car's manual for more information.
If you need more help, reach out to Apple Support directly so they can look into this with you further. They can be contacted here: Contact Apple Support or by calling the most applicable phone number from this list: Contact Apple for support and service.
Kind regards.
