Warp to Manana Island
First, find and GPS-mark the hitchhiker Mario's location. It is on the bottom right corner of the island. Just below that is the time race "The Saleen Classic". Directly to the top left of the stopwatch icon is the blue motorway. See that little clearing of trees? Warp next to it, and drive straight up the grass. Follow the edge of the cliff for about 0.7 miles (until you are almost directly above the GPS mark), and eventually you will see a blue 'e' logo. This is the logo of Eden Games, the producers of Test Drive Unlimited. You need to drive straight into this logo at 40 mph (64 kph) and hit enter. You will be warped to Manana Island - a possibly unused portion of the game. None of the roads are registered as discovered so you may want to place a bookmark here to save the hassle of driving to the 'e' each time.