Rewards: 66 Gold, R$66,000
Location: SEASON 2
Unlocks from: Owning Any Car In Series
Maximum Required PR: 61.3

There are 51 events - 48 Trophy + 3 TT - with each car having a specific TT and 2-event Showcase.  Suitably upgraded any one car can reach 75%, but only the Speedster can be upgraded enough to open up the last 3 cup races (PR 57.6/59.4/61.3)

Progress Rewards split:
25% - 8GC and R$8,000      [PR 43.4 using Boxster, otherwise PR 45.8]
50% - 13GC and R$13,000   [PR 47.4 using Boxster or 458, PR 50.3 using Speedster only]
75% - 18GC and R$18,000   [PR 52.4]
100% - 27GC and R$27,000  

When the Speedster becomes available the upgrade costs will be:

(Thanks as always to Paulo on FB at RR3 Trackside)