Standards
How we measure, classify, and document the vehicles in the Auto Heritage archive.
Power
All power figures use the manufacturer's official rating at the time of production. For European vehicles, this is typically PS (Pferdestarke, metric horsepower) or kW. For vehicles with American-sourced engines (Jensen Interceptor, De Tomaso Pantera), we use SAE horsepower.
1 PS = 0.9863 hp (SAE). The difference is approximately 1.4%. We display all figures as "hp" for readability, but European figures are metric PS unless otherwise noted.
Example: The Porsche 993 Carrera is rated at 272 PS (268 hp SAE). We display "272 hp" using the manufacturer's PS figure.
Weight
All weights are kerb weight (DIN) in kilograms, measured with a full tank of fuel and all standard equipment but no driver or passengers. Where manufacturers provided multiple figures for different markets, we use the European DIN specification.
Performance
0-60 mph times are sourced from period manufacturer claims or verified independent tests (auto-data.net, manufacturer press releases). Top speed figures use the manufacturer's stated maximum. Where multiple sources conflict, we use the manufacturer's official figure and note discrepancies in the source links.
Engine Displacement
Displacement is listed in cubic centimeters (cc) using the manufacturer's official figure. Descriptive labels (e.g., "3.0L") are rounded approximations. The exact displacement is always available in the specifications table.
Production Numbers
Production totals include all variants of the listed model unless a specific variant is documented separately. For example, the W124 production total includes sedan, coupe, estate, and convertible body styles. Where a specific variant like the 500E is listed separately, its production total covers only that variant.
Model vs Variant
We distinguish between models and variants when they represent fundamentally different vehicles. A Mercedes W124 300 E and a W124 500E share a platform but differ in engine, suspension, body panels, and character. They are documented separately.
When a variant represents a minor update (facelift, power increase, equipment change) without changing the car's fundamental nature, we document the most representative version and note the variant range.
Year Ranges
Year ranges reflect the production period, not the model year. The start year is when the first production car was built (not when it was announced or shown as a concept). The end year is when the last unit left the factory.
Estimated Values
Market value estimates reflect approximate prices for good-condition examples in the current market. Ranges account for specification, condition, provenance, and market fluctuation. These are not appraisals. Actual transaction prices depend on individual vehicle history, documentation, and market conditions at the time of sale.
Sources
Technical specifications are sourced from manufacturer press releases (BMW PressClub, Porsche Newsroom, Mercedes-Benz Media), verified databases (auto-data.net), and official factory documentation. Every vehicle entry includes source reference links where available. When sources conflict, we note the discrepancy and default to the manufacturer's official figure.
Editorial Independence
Auto Heritage is an independent digital archive. No manufacturer, auction house, or commercial entity has editorial influence over vehicle selection, significance assessments, or heritage classifications. Our documentation reflects research and editorial judgment, not commercial relationships.

