I do quite a bit of furniture restoring and one of my old tricks worked pretty good on the car leather.
Note that the black top grain cracks and exposes the lighter grain of the leather underneath. You can buy an inexpensive bottle of liquid India Ink from the art store, and a very VERY fine brush, and paint it onto the cracked areas. The liquid wipes right off of the slick top part but dyes the porous exposed part.
My seats went from Gee-I-need-to-re-skin-soon to Hey-its-fine-I-never-even-notice.
And if you're wondering, no, the dye does not get onto your clothes. It dries and it never comes off. I've thought of re-skinning but now I can't justify that expense. The seats are fine.
Estimated costs for ink and brush: approx. 5 bucks.