Hello Gameloft !
Firstly, Why not let the players choose whether they want to race in short, long, or very long type of track. The trophies increment also depends upon the length (short, medium, long, very long). Also there can be multiple laps of the long tracks(60") irrespective of the league.
Secondly, If possible, allow the players to race with their in friends connected via Facebook and also from the same Android or ios platforms.
Thirdly, Could to bring back the ghost season once in a while. This way the really skilled players can get at the top of the leaderboard