Generous offer from the Monkeys of 100% fame bonus for the next two days - which means the next update will be EXPENSIVE with the 4 GT3 cars (NSX, 488, M6 and Huracan).
Farm away and grind out those Le Mans laps - and use an agent with every 10 lapper you can face!
EDIT: 10 lapper (2014 Porsche, tier 5.1) + agent + Daily reward bonus 100% fame + 2 days 100% fame bonus = 227,200 fame points (ie they all count)
(and at level 377, that was about 80% of a blue game bar = 50 GC)