Here's what it looks like in the suburbs of a big city. But I was thinking about the forces under a car's tyres. Typically, I draw friction as a backwards force under the wheels of a car - a counter force to its motion. But think - the car engine provides torque to turn the wheels. The contact between the rubber and the road means that the tyre tries to push the road backwards. By Newton's Third Law the road must try to push the car forward. The road is heavier and it doesn't move. So you can argue that it is friction that is the force pushing the car forward. Try this Durham University page as an example: http://www.dur.ac.uk/r.g.bower/public_html_old/PoM/pom/node16.html
