Select the Panoz GTR-1, then drive as fast as you can down the Golden Gate bridge. When you hit about 200 mph your car will start to bump on the road. There is a spot in the road to the right at the end of the bridge where it will shoot you up in the air if hit just right. This will shoot you over the tunnel. You can then drive over the hill and out into a huge open area that you are not supposed to be able to reach. Note: This may require a few attempts.