The usual extra info on this series for the Alfa Romeo 155 V6 TI, along with the Nissan Skyline GT-R Group A...

There are 54 events (52 Trophy + 2 TT) with each car having a specific two-event showcase +  TT.  The rewards  25-50-75-100% are split 8-13-18-28GC, and either car can be upgraded enough to complete the series.

With just the Alfa at its Race Day completion PR of 54.6 you can easily get to 75%...

...and obviously the Nissan alone could do the same.

It costs a further 156GC to upgrade the Alfa enough to complete the series (full upgrade tree at https://myrealracing.club/thread/38319/special-event-race-da...)