The slickest trick that I've found for sprucing up an interior, either leather or vinyl is, believe it or not, shoe polish. Yes shoe polish, cost under $1.00. If you have a black or brown interior with a faded dash, seats with scuff marks or cracking, wear through, etc., the shoe polish will darken the imperfections and even make them glossy again.
If your interior is white, it can do wonders for brightening up the color and covering up a lot of imperfections.
No, it won't rub off on your closes, and it lasts a fairly long time. Perfect for use prior to shows. Heck, you can even make dirt or grease shine with it.
For disbelievers, try a small area on the back of the front seat or low on front of the front seat.
It also works very well on the white haze left in hard to reach spots or uneven surfaces left over from a wax job.
Try it sometime,
Paul
PS
I'm referring to the wax kind in a can, not the liquid kind in a bottle.

 

I use black shoe polish on my inner fender liners!

 

I know we used to use it on black vinyl tops. I'm going to try it on my plastic inner fenders.

 

You can also use it to make a Groucho Marx mustache. This may or may not improve your car ownership experience. ymmv