Hit The Pavement Meaning

(idiomatic) To travel or begin to move in an automobile or other road vehicle.

Example: 2007, Ceri Au, "Fighting for the Right to Flush," Time, 31 July:
  But getting people to hit the pavement is more than just a health concern. . . . [M]unicipalities are looking to combat inner-city decay by keeping the streets flush with pedestrians.
1925, "Automotive Section: "Hitting it up" (advertisement)," Ottawa Citizen, 4 July (retrieved 28 Sep 2010):
  "And when we hit the pavement, we found we had covered the last 54 miles in an hour and twenty minutes."