Porsche Unleashed was exceptionally well done. And you're right I did forget. For some reason I never consider it to be part of the NFS series. Probably because 98% of the NFS titles were terrible!
57 different Porsches, truly amazing! It was a great experience to go through the evolution of Porsche and adapt to the handling differences between cars. We may never see a title that ambitious and focused on a single car manufacture ever again.
I am surprised car makers in 2019 don't fund singular titles similar to NFS PU or at the least funding expanded DLC for Assetto Corsa or similar racing sims as a means of promoting their brand