Complex sentence: The Xbox version is subtitled the "Developer's Cut" and it features 21 new car skins and an Xbox Live online leaderboard, which was the first use of Xbox Live in a "Burnout" game.
Split into simpler sentences: The Xbox version is subtitled the Developer's Cut, featuring 21 new car skins. It also features an Xbox Live online leaderboard, which was the first use of Xbox Live in a "Burnout" game.