I've tried a lot of different car products and can't find anything that works better than Armor All and it doesn't work very good. Stoners Trim Shine will put a nice gloss on the plastic and vinyl but it doesn't last very long. Back To Black works OK on the black polymers and plastics but you would think someone makes a product that could do better.
Meguiars natural shine.....and gold class for the leather (if needed)...there are a lot of good ones out there...but a lot of us car show guys use Meguiars
NONE OF THE SNAKE OILS will keep the plastic from cracking. The only thing that REALLY works is a carport or garage. I've used "em" all. All just make a shiney finish for a short time........The UV can't get it "iffen" it can't see it.
Another nod for 303 Aerospace. It leaves a nice satin finish if used as directed and has UV inhibitors. As Mike,SC Hunter mentions nothing beats not letting a car sit in the sun all day.
I remember treating my car's interior with stuff like that a few times when I first got it -then concluded it was one big waste of time and never did it again. Used the car for eighteen years and the interior looked like new without the stuff. Haven't used it since.
I use Maguires Gold Leather Cleaner, Conditioner, Protectant (one product does all 3) in both the cream and spray versions. The cream is great for solid leather while the spray is thinner and won't clog up the perforated holes in the seats that have them. It is also safe for vinyl.
For vinyl treatment, look at Marine products for boat interiors. Most are vastly superior to ArmorAll and are specifically designed to help with UV damage.
Many of them make ArmorAll look like water by comparison.
Armour-All on the interior of a car will evaporate and leave a haze on the inside of the glass that is very stubborn to remove. Windex will do it in 3 or 4 tries. ask me how i know.