Hi Sajadzi,
Since you have turned off Automatic Ear Detection and they still connect, let's rule out an issue with the AirPods software by resetting them: How to reset your AirPods and AirPods Pro - Apple Support
This also may be happening if the connection drops from the car stereo, so we suggest checking for an update for that unit. You may have to check the car manual for steps to do so.
We also recommend restarting your iPhone and keeping it updated as those steps assure you have cleared out any minor software issues and are running the most current version.
Restart your iPhone - Apple Support
Update your iPhone or iPad - Apple Support
If you still have questions, reach out to Apple Support directly, as this may require closer guidance: Get Support
Cheers!