You can do things faster and you have more possibilities to mess with the layers you want. Flip is something that will save you from doing annoying time consuming moves (probably one of the most important improvements that Forza 7 has brought to the series).
Use arrow keys on keyboard to change the numeric values while altering and moving objects (hold down shift to make bigger numeric change). To flip with tab key hold down tab (you have to be in the move tab in change position sub-menu) and press up/down (vertical flip) or left/right (horizontal flip). Mouse is only good for zooming in and out and looking around the car (OK, good for freely moving an object too, but not for precise movements).
The favourite colours isn’t working for me, the colour just reverts back to the car’s default manufacturer’s colour.
I’m really surprised at how buggy this edition of Forza is, the livery editor is really broken, I suspect because it hasn’t had a proper overhaul in years - it’s still essentially the same as introduced in FM5.
I like this especially. It saves time if you don’t want to have to fine-tune the same color over and over again for different cars. The “Previous” tab works up to a point, but doesn’t save them when you close the game.