My steering wheel and my stick shift are worn out by the sun and 11 years of usage.
For 50 bucks you get them as new.
For this you need some professional leather products. I am using here products from Colourlock.
So I needed a degreaser (essence de nettoyage cuir), ultra fine sand paper (look like a sponge), leather paint (black but any color exists) and leather varnish (sellement cuir). Brushes are for the paint, cloth is for the varnish.
You protect the plastic part of the dashboard.
You sand down the dead part to make it smooth again.
Then you use the degreaser to clean the leather.
You paint using a brush from a hobby store. Two layers.
Once dry you apply the varnish with a cloth (no rubbing otherwise the paint will go). The varnish is here to settle the color and protect it from UV and dirt.
Then when completely dry you can apply some leather cream. It is important to use one with neatsfoot oil to soften and protect the leather.
All this can also be done on the seats. Colourlock sells liquid leather to fix scratches if need be.