After practicing with a friend today and using this feature it proved very useful to both of us, however, 2 major flaws.
1: why the cost of engine parts and stamina? 305 days ago you said this would be changed sooner rather than later (yes I've searched the forum for similar posts)
2: make it easier to invite other people... Send a message or email or messenger invite that then opens the browser not the app and then download the 3d viewer... It really makes no sense.. Why not just click on the friend(s) you want to invite and go!!
We ended up doing 2 races because it was hassle using multiple platforms to race on the game which essentially is an app or browser...