If they are the same material as the Jeep Grand Cherokee cladding (which I assume they are, since it's all DC) then you can use any good trim and/or tire dressing. I use either Meguiars Trim & Tire dressing gel or Armor All Detailer's Advantage tire foam. Both leave a nice sheen and last pretty well.
Other good products are Turtle Wax Tire Wax, 303 Aerospace Protectant, Original Armor All, and Meguiar's Dash Foam. All will do the job quick and cheap. Be sure to buff off the excess, after application, to avoid runs.