Rewards: 57 Gold, R$57,000
Location: SEASON 1
Unlocks from: Own Any Car In This Series
Maximum Required PR: 16.5

There are 54 events - 52 Trophy + 2 TT - with each car having a specific 2-event Showcase + TT.  Either car can be upgraded enough to open the last cup race...obviously both are required to get 100%, but assuming you already have the Merc there will be no need to spend anything on the ‘free’ BMW if you don’t want to!

Gold progress rewards are:
25%  -  7GC
50%  -  11GC  [PR 12.4 if only using BMW, a bit less if using Merc]
75%  -  15GC  [PR 14.3]
100% -  24GC