With authentic cars, courses, and car physics, Gran Turismo 4 adds an even more realistic racing simulation to the series. The characteristics of each car take into account weight, speed, friction, and more to deliver realistic handling. Test-drive new vehicles in courses located in various sites, such as Nurburgring Nordschleife, New York City, the Grand Canyon, and Tsukuba Circuit. The PSP version of Gran Turismo 4 lets you race against your friends via wireless network.