To confirm if you are already on the new Xbox app, please look at the tile for the app from your Xbox's list of apps. You want the one where the tile has a red background and white text, and not the one with a black background that also says "ON DEMAND" (the Old App). You can try to look for it on your Microsoft Xbox Store search box and type “MotorTrend” with no space or use the link above. This new app was rebuilt from the ground up to be more stable, and so that we can more easily add new features in the future.
If you want to see what other platforms we currently support, then please be check our supported devices page for the latest list of supported devices. This list can change, and we are working to add additional platforms. If you don't see your platform there, you can submit it to us as a feature request and we will evaluate it for future development.