I recently ran the PD Cup in the ZZ-S. Although i don't have a detailed writeup like
Neon_Duke, i do have a few things to add.
I was able to win most of the races using T3's and a no-pit strategy. Some of the longer courses (grand valley) required a one pit strategy, which caused a slight disadvantage. The T3's could last around 15 out of 20 laps. When a one-pit strategy was required, i would usually head in around 10-12 laps, on yellow tires, which felt like a waste. however, it would have been pretty difficult running the last few laps on Red tires. It might be smarter to buy a few sets of tires, and adapt your strategy with the different tracks.
I came in 2nd at Seattle, which I found to be pretty difficult. The lack of power, due to dirty oil, is pretty frustrating. especially when the AI starts putting up decent lap times on Red tires.
I won another Escudo, which i promptly sold

one is enough for me.
There were a few minor notes i wanted to add, but they escape me at the moment.