We discover new places by hitchhiking. With hitchicking you can see the whole world and meet a lot of new people. To sleep and travel for free there is http://www.couchsurfing.org/.
Why not use the empty back seat? Yes, let’s use it. They call it hitchhiking. Standing besides the road and a sign in your hand with the name of the place where you want to go. Here you can read about how to hitchhike: http://hitchwiki.org/en/Top_Tips
If you are going to hitchhike, is to do it with with a good friend. The combination of a boy and a girl works the best. If you don’t got a girl, hitchhike with a boy. This works but only takes a bit longer.
If you want to hitchhike, always start with a gas station on the road you want to go.
To find hitchhike hotspot, you can search on this website. At this website is a map of the experiences and tips on that particular spot. http://hitchwiki.org/maps/
At the gasstation you can start to ask everyone with a car, truck or bus where they are going and maybe you can drive with them. So thumbs up!