In the car I cannot read new messages with the phone locked

Hi there, Nathan,

Thanks for visiting the Apple Support Communities. I understand from your post that when you're in your car, and you ask Siri to read your new messages, Siri says the phone must be unlocked. I'm happy to help!

This behavior is caused by your phone's Notification settings. If you go to Settings > Notifications > Show Previews and change the feature to "Always", Siri will be able to read your messages while you're in the car, without you having to unlock the phone first. Please keep in mind, though, this will mean your full notifications will always show on your lock screen, instead of being masked until you unlock your phone.

For more information about notifications on your iPhone, check out this article:

Use notifications on your iPhone, iPad, and iPod touch

Cheers.

We're glad to hear that the issue is resolved, Nathan!

Happy texting!