I feel that one thing that has been missing from Forza is the ability to do turning and painting on a mobile device. GTA V had an app which allowed some of the painting and management of vehicles. I feel that garage management is slow on the console, and it would be helpful to do it on another device or even while away from your Xbox/PC.
I also feel this could increase the amount of tunes, community for paints and overall continuity of the game.