See Hagerty:
www.hagerty.com/apps/valuationtools/1988-Porsche-928-S4
Current Values
#1 Concours $55,900
Condition #1 vehicles are the best in the world. The visual image is of the best vehicle, in the right colors, driving onto the lawn at the finest concours. Perfectly clean, the vehicle has been groomed down to the tire treads. Painted and chromed surfaces are mirror-like. Dust and dirt are banned, and materials used are correct and superbly fitted. The one word description for #1 vehicles is "concours."
#2 Excellent $38,700
#2 vehicles could win a local or regional show. They can be former #1 vehicles that have been driven or have aged. Seasoned observers will have to look closely for flaws, but will be able to find some not seen by the general public. The paint, chrome, glass and finishes will all appear as excellent. No excessive smoke will be seen on startup, no unusual noises will emanate from the engine. The vehicle will drive as a new vehicle of its era would. The one word description for #2 vehicles is "excellent."
#3 Good $27,900
#3 vehicles could possess some, but not all of the issues of a #4 vehicle, but they will be balanced by other factors such as a fresh paint job or a new, correct interior where applicable. #3 vehicles drive and run well, but might have some incorrect parts. These vehicles are not used for daily transportation but are ready for a long tour without excuses, and the casual passerby will not find any visual flaws. "Good" is the one word description of a #3 vehicle.
#4 Fair $12,500
Value Adjustments
-20% for auto.
