text messages not receiving while in car

Another place to check is as follows:

Settings > Bluetooth> tap the little circle with i in it next to your car system name

Make sure Show Notifications is turned on. If it was off, this is why you're not getting text messages in your car.

As you have Driving set to manual, check the Control Center to see if DND while Driving is enabled:

If you don't see this icon in Control Center go to Settings/Control Center and add it.

Are you not receiving the messages at all, or are you just not being notified of them?

If you're connected to the car using bluetooth, and the head unit supports A2DP audio streaming, you won't hear any notification sounds from the phone unless the audio system happens to be tuned to the bluetooth audio source. This is completely normal when you're connected to any bluetooth audio device. Notification sounds are routed to the bluetooth device instead of being played on the phone.