We already knew these facts:

Cars: 1999 NISSAN SKYLINE GT-R V-spec (R34), 1990 Mercedes-Benz 190E 2.5-16 Evolution II,
Rewards: 44 gold, R$44,000
Location: PRO/AM
Unlocks from: 28 Trophies in V8 Naturals
Maximum Required PR: 17.0
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Just for the record the rewards split 5 @25%, 9 @50%, 12 @75%, 18 @100%, and you need the Mercedes for its Showcase, TT, and the final Cup race...a fully upgraded Skyline gets you this far: