For the wheel wells and other under car areas, you can use Orange Agent to help break down dirt, mud, grease and other contaminants. Spray liberally to all the areas you wish to clean, and then agitate heavier soiled areas with a brush like our Big Black One, Little Chubby or Big Boy Brett brush. While the product is still wet, pressure wash off, or rinse thoroughly with your hose. For plastic wheel arches, you can dry them thoroughly with a cloth like our Twisted Little Sucker or Dirty Deeds cloth, and then apply Vinyl Revival to protect them.