I use this stuff quite a bit in my mobile detailing business. The results you'll get is all about A.) how discolored  the area to be treated is, B.) The amount of discoloration variation on the area treated C.) the prep. work, and. D.) Realistic expectations if A. and B. are 'fairly bad' to 'OMG that looks awful and I can't stand it anymore.'To be frank, the cleaner included isn't so great. Especially if there is relatively heavy wax/silicone/sealant build up on the area to be treated. My recommendation would be to first use the provided cleaner as directed; then, after rinsing and allowing to dry, useGriot's Garage 11071 Rubber Prep - 16 oz.as directed. THEN (bear with me) clean again with the cleaner provided by Forever Black. Then, and in my opinion only then, will you have a properly prepped surface to apply the Forever Black dye.To be frank, if there is a circumstance in which the Forever Black dye can only be applied once (one layer) with satisfactory results (even after all of the above prep work) I've just never run into it. For one, the applicator is overly porous foam: foam holds air: air makes bubbles: bubbles make imperfections in the application. Second, you've got to have next to perfect/new trim to start with for this product to not streak...and even then it streaks a bit. In the end, severely weathered trim will need about 6 or 7 passes for the people who are willing to buy this stuff to be happy.Even though I use Forever Black quite a bit, I'm only giving it three stars for the following reasons:1.) The cleaner provided... is not good.2.) Forever Black (the company) absolutely must know that the applicator is sub-optimal.3.) Unless your car is new or next to new, there is no way at all, not even close, no chance, that one bottle of dye treats 4 - 6 cars. In fact, you will be lucky to get all of the rubber, plastic and vinyl all the way around a single mid-sized sedan with one bottle of dye. (as a point of reference, one bottle of dye is exactly the perfect size to treat all of the rubber, plastic and trim on a severely weathered 2000 BMW 323i.)Happy Detailing!AJBest-Auto-Detail.comP.s. I wanted to add that when using the dye it is imperative to resist the temptation to apply more and more dye to fix the streaking, PRIOR to each application/layer having had a chance to dry. If you do this, it will flake off sooner or later. Especially if the surface wasn't prepped as described above.