Mad Tracks has a single player mode and a multiplayer mode. In single player your objective is to achieve the highest trophy (Gold) by completing objectives, from racing around a track to landing your car on a face-down dart board.
In Mad Tracks online it is very similar to the single player. You can have up to 4 players in a single game and if you are the host you can choose the level you play at with the same objectives as single player. There is another feature allowing you to change the color of your car easily accessed by the Xbox 360 controller 'x' button, Allowing you to cycle through red, blue, yellow, green, purple, pink, black
In single player your task again is to complete the set tasks. You compete against the computer and at one point you have an ally helping you (Foosball) When you start the game you will be given a block of levels to complete.
Source: Wikipedia, "Mad Tracks", available under the CC-BY-SA License.