The model is only the starting point. Within any exotic there are cars that collectors chase and cars that sit. The difference is in the details.
Color
Special-order and one-off colors, period liveries and well-chosen combinations make a car stand out. A common color with no options is usually the least desirable version of a model.
Factory personalization
Programs like Ferrari Tailor Made, Porsche Paint to Sample, Lamborghini Ad Personam and McLaren Special Operations let the first owner go beyond the standard options list. These cars are often one of a kind. Here's how the programs differ.
Carbon, seats and interior
Exterior, interior and engine-bay carbon packages, colored or exposed carbon, carbon racing seats and unusual interiors can lift an otherwise ordinary spec.
The gearbox
For some models, a manual gearbox is the most sought-after version, especially where few were built. See the manuals worth hunting.
Mileage and condition
Lower mileage generally helps, particularly on collector cars, but it isn't everything. Original paint (checked with a paint meter), condition and how the car was maintained matter just as much.
Documents and story
A window sticker, build sheet, books, keys, service history, few owners and a known story all add confidence, and confidence adds value.
The question to ask about any car: what makes this specific one desirable? If you're not sure, ask Eddy.