Looking back on 2015 we now believe that all 928 values have risen and that if your car is in good condition visually and mechanically, with a well-supported service history, you should now consider increasing its value for insurance purposes, at the very first opportunity.
Early in 2015 it was still uncertain if only the very best cars were achieving high prices but the market seems (at last) to have recognised that the 928 does have a rarity value. Details of individual models and a price analysis can be found in the complete article in the 928 Register section of Porsche Post March edition.