The usual extra bits of info...
There are 51 events (48 Trophy + 3 TT) and the 25-50-75-100% progress gold splits up 8-13-18-27GC.
Each of the three cars has a specific two-event showcase and TT...with the 240Z R3 (PR43.1 from its LTS) you can surge past 50%, then adding the Skyline R3 (PR47.9 from its LTS) gets you beyond 75%:
(That leaves the 370Z R3 showcase and TT, together with the last 4 Cup races at PR 50.3, 53.3, 56.5, and 59.7)