It is common practice for manufacturers to test new software features on their own hardware before rolling them out en masse. A perfect example of this is how Google Assistant and Google Lens were Pixel-exclusive features at first and then begin rolling out to other devices after Google ironed out the kinks. Similarly, a feature on the Pixel 2 would automatically enable Do Not Disturb Mode when you’re driving was tested some time ago and now it has been rebranded as “Driving Mode”, and it is showing up on multiple non-Pixel devices.
Driving Mode is an essential feature as it goes a long way in reducing the distractive effects of a smartphone. Given our conditioning, one would immediately reach for our smartphone upon receiving a notification. The fraction of a second that it takes to swipe it away is enough to put the driver at risk of a potentially fatal accident. Texting and driving have been found to be the cause of several road mishaps, and very often, the person at the receiving end has to bear the brunt of an idiot who couldn't wait five minutes to respond to a text.
Google has been working to prevent those distractions from resulting in collisions and death. One way they are doing this is by using their new Driving Mode that has been added to the Google Play Services application. With the feature enabled, once the smartphone detects you are driving it will either enter Do Not Disturb mode or it will automatically launch a car-friendly app (such as Android Auto). You should see the new option in your Connection preferences in Android 9 Pie.
Now, you might ask, how does Google know that you're driving the vehicle and not a passenger. To be honest, it doesn't. If you are indeed a passenger, you can switch Driving Mode off by heading over to your devices' connection preferences.
News Source: XDA developers