This only work in Keys To The City, which is available for download from the Xbox Live Marketplace. During game play, press Back and set all of your skills to four stars. When you get in the truck cab, it will morph to the largest possible. Enable "God mode" so you can't die while attempting the jump. Also choose "Empty streets" so you do not hit cars in the process. Go onto a straight and long freeway and hold B to speed it up, then press Back. Select "Spawn ramp truck". When you are going about 190 mph, hit it, then change the camera angle to the side of the truck. Then, press Y to spawn the ramp truck and begin the glitch. You will fly for a very long time.