The Mario Kart Channel is a feature in Mario Kart Wii and Mario Kart 7 that utilizes Nintendo Wi-Fi Connection (Nintendo Network for MK7). There is a similar feature in Mario Kart 8 called Mario Kart TV.


Mario Kart Channel's menu


Mario Kart Wii

Mario Kart Channel
The Mario Kart Channel is a downloadable channel that allows access to special game modes related to the game's use of Nintendo Wi-Fi Connection, such as tournaments, ghost races, and Friend Code Registration. You can also look at your Time Trial ranking compared to your Friends, National, or Global. The channel can be downloaded to the Wii Menu and can be accessed without having a Mario Kart Wii game disc inserted in the Wii. However, the disc must be present in order to participate in a race or tournament. 

Mario Kart 7

My current Mii in Mario Kart 7
The feature is not to be downloaded onto the system but is instead accessed through the game's main menu. Players can view Time Trial ghosts received through SpotPass and StreetPass, as well as race them, see a list of StreetPass tags, and view personal statistics such as wins, losses, coins collected, VR (Versus Rating), and the amount of StreetPass tags you have received as well as the player's title. You will also be able to customize your own kart combination for your Mii to use(kart, wheels, glider) when people who have exchanged data with you via StreetPass want to race you. You can also customize your own Cup for other people to play, just like Grand Prix