Universe
U.S.-market public asks and auction outcomes for the Porsche 964 Carrera 2, Carrera 4, RS America, RS and Turbo. European records remain a separate comparison layer and never enter U.S. medians or liquidity measures. Data collection began September 18, 2026.
Blank fields remain unknown until evidence populates them. Unknown never means No.
One car, one identity
One physical car keeps one Vehicle ID. Permanent identity and specification belong to the vehicle or its typed attributes. Mileage, condition, originality and service status belong to dated observations.
Car, observation, market event and price observation are separate objects. Public views join them without overwriting source facts.
Market history
Each distinct attempt to sell is a Market Event. A continuous listing remains one event while every observed price change becomes a new Price Observation. If a car leaves the market and returns, the Vehicle ID stays the same and a new Market Event begins.
Effective Date records when the underlying event occurred. Observed At records when Madrid learned about it.
Asks are not sales
Asking prices, recorded sold outcomes and reserve-not-met bids stay separate. A disappearing listing is not treated as a sale. Europe prices are displayed in native EUR unless a dated, documented conversion is supplied.
Venue identifies the actual marketplace or seller; Source identifies where the record was obtained. Days listed appears only when a defensible listing date exists. A first-observed date is never presented as the original listing date.
Comparable cohorts
Major families remain separate. Turbo 3.3 and Turbo 3.6 are treated as distinct pricing cohorts. Within each family, comparisons narrow by body, factory transmission, NA or ROW specification and mileage before originality, engine history, paint/body history and meaningful factory equipment are considered.
Median-band or premium claims appear only when enough usable records survive the selected sequence. An unpopulated field never becomes a negative observation.
Evidence and quality control
Assertions can be Confirmed, Documented, Reported, Inferred or Unknown, and multiple pieces of evidence may support or contradict the same fact. Every derived valuation preserves its cohort definition, analysis date and data cutoff.
Impossible prices, malformed values and restomod records mapped into standard factory cohorts are quarantined from charts, medians and market calculations until reviewed.
Price × mileage requires at least five valid observations. Family trend bands require at least eight observations, adequate mileage dispersion and at least three observations inside a mileage band. Time-series charts require three distinct periods. Market View shows separate family series and never calculates one blended 964 trend. When a threshold fails, the underlying records remain visible without a decorative chart.