TwoCredits

This game has been announced as supporting the Nintendo Wi-Fi Connection service. This will feature online racing and battle modes, both of which are capable of up to 12 simultaneous players. It has also been confirmed that there will be online leagues, with international and local rankings. This will take place from within an entirely separate Wii Channel. This channel will also feature the option of sending saved time-trial ghost data

And that folks is why it's a must-have game.