The usual extra info on this series, for the Ferrari F500 TRC and Jaguar Lightweight E-Type ...

There are 54 events (52 Trophy + 2 TT) and the rewards 25-50-75-100% are split 8-12-17-26GC.  You need both cars for 100% and only the Ferrari can be upgraded enough to complete the series, but a fully upgraded E-Type will get you well past 75%:

The  final three cup races are PR20.5/22.5/23.9, and I gather it will cost 148GC more (possibly less in you're rounding lucky) to upgrade the Ferrari enough (over and above the initial LTS-winning cost which will apparently be 153 cost -25 reward = 128GC).