Apple just seeded the fourth beta of iOS 10.3.2 to developers. This update comes one week after the last release. We do know that there are some SiriKit car command fixes. Other than that we’re unsure what’s new in this version, but it likely includes some bug fixes and other minor improvements.
Developers with the testing profile installed can download the update from the Settings app. If you’re not on the beta yet you can get the testing profile from the developer center.