Why are Porsche 914 Prices Flat?

From 2015-2018 Porsche 914 owners saw the value of their 914 on the rise as the 914 was swept up in the massive price appreciation of air-cooled Porsches. But since 2018, prices have been flat. There was speculation that the 50th anniversary of the 914 in 2019/2020 might help to spike the prices but that didn’t occur.