Patina
 

Can someone please explain to me the difference between worn out and "Patina" when referring to areas on a car ?

I often see leather that looks knackered to me but owners delight in saying they are looking after the natural patina. Same goes for woodwork but not tyres and paint but not pistons. I guess there is a fine line but not many would sit on a musty sofa at home with holes in it ! apart from me :-)

Greg - old but good patina

Patina
 

First one I found:
Definition: a surface appearance of something grown beautiful, especially
with age or use, which adds value to an antique or collectible and should
not be cleaned >
Hence, not tyres, and probably not pistons, if they need to be functional.
I would personally hesitate before repainting an engine block - even if it
is in the correct shade of green.....

...patina...
 

"Worn out" is when we buy. "Patina" is when we sell. ;)

Once the car goes past the Patina stage it becomes a "Restorer's Delight".

Then the most valuable of all is often the "Barn Find" (especially if it an Aston).