G4: "In Single Player, you can select several options including Grand Prix, a series of races that is the closest option to a career mode, or Quick Tour, which is probably my favorite mode. You tell the game how long you want to play, and what type of course you want to race on (Recommended, Drift, High Speed) and what type of car you want to race in. The game will generate a course for you and drop you right into a single race, or a series of races depending on the time you selected, up to 30 minutes.
Other race types include One-Make Race, where all of the racers use the same type of car, and StreetPass Duels where you can race against the ghosts of people you’ve passed on the street. If you’re just looking to jump in and try things out, select QuickTour or Standard Race, but if you really want to kill a lot of time, Grand Prix will keep you gaming for hours."