Leather Manufacturer's Representative
As a person who spent 50 years in the furniture business (20 with my own stores) other comments have some truth to them but the real story is worse. Bonded leather, which is what you probably have in your vehicle, is ground up and shredded pieces of leather that are then bonded (glued) to a piece of vinyl. What you sit on and touch is vinyl not leather. The leather is on the backside where you cannot touch. They should call the product bonded vinyl.
If you treated it like leather and used oil based cleaning materials to "to soften it" you ruined it. As with all vinyls...to clean it you should use water on a damp cloth. Remember it is a form of plastic made by bio chemicals.
Replacement: if I was going to replace what you have in my vehicle, I would go to a custom order furniture store and buy a couple of yards of "bonded leather material". A yard of material (36" X 54") costs the retailer about $5 plus freight. An expected sale price to you would be around $20. (Heh they have to make money somehow) Then I would find a local reupholsterer to redo the seats.
Now...you could reupholster with real leather...but your cost would be about $30 a square foot or about $400 for enough leather to cover the same amount as the 36" X 54" $20 product. But the challenge would be to find a good enough reupholsterer who is qualified to work with leather.
So...I'd go with the bonded leather, clean it with water, and expect about a good 8 years of wear out of it.
By the way the bonded manufacturers have gotten so good with their product that I've sat in furniture manufacturer's meetings where the reps could not tell the difference unless they turned it over. The bonded producers can put distress marks, cattle brands, skin patterns, scar marks and scent on the bonded so you think it is real. Hope this is helpful.!