WhatsApp is now supported on Apple’s CarPlay. WhatsApp will automatically show up as an app when your iPhone is connected to CarPlay. It’ll work like any other messaging app due to Apple’s strict rules for CarPlay messaging apps.
WhatsApp 2.18.2 for iOS, when you plug in your iPhone into a CarPlay-compatible vehicle or aftermarket head-unit the icon for the messaging app is automatically added.
The new functionality was first reported by iCulture. Press the icon, and you get the option to either dictate a new message or hear a spoken summary of currently unread messages.