Original cost and resale value are different things
A factory option that cost thousands when new will not politely retain the same amount for the next owner. Its resale contribution depends on demand for that feature on that model, how common it is and whether it still works properly.
Some options create a visible price premium. Others make a car easier to sell without changing the headline figure very much. Both effects matter when you are choosing between otherwise similar examples.
The right option depends on the car
A panoramic roof, premium audio system or driver-assistance package may be considered essential on one luxury model and a pleasant curiosity on another. Body style, climate and regional preferences all influence what used buyers search for.
Colour combinations matter too. A rare paint and interior pairing can be wonderfully desirable to a small group—or narrow the audience to three people, one of whom already owns one.
Condition can swallow the premium
An inoperative roof, cracked large wheel or obsolete entertainment system can cost more to repair than the option adds to the car. Buyers value equipment they can use, not merely an impressive code in the factory record.
Replacement and retrofit parts should be described honestly. A newer head unit may be an improvement, but it should not be advertised as original factory equipment if the build sheet says otherwise.
Use the specification as evidence
A factory build sheet helps you name packages correctly and avoid overlooking valuable equipment. Pair it with clear photographs, service documentation and proof that the major features operate as intended.
For a formal valuation, look at current comparable sales and seek professional appraisal. There is no trustworthy fixed percentage that can be applied to every option, every model and every market—however convenient that spreadsheet would be.