The usual extra info on this series, for the Lamborghini Aventador SVJ, plus Ferrari F8 Tributo and McLaren 720S...

There are 51 events (48 Trophy + 3 TT) with each car having a specific two-event showcase + TT.   The rewards 25-50-75-100% are split 9-15-21-32GC, with only the Aventador able to be upgraded enough to complete the series.

You can reach 75% with the F8 Tributo alone, fully upgraded (PR72.2)...

...and obviously the same would apply with just the 720S upgraded to that PR.  With both fully upgraded you get to 90%...

Note that the final race is PR78.0 not PR78.2 as stated in the patch notes (no cost saving though!), and those costs of upgrading the Aventador enough and indeed those of winning it in the LTS are as below, as usual courtesy of Paulo over on Facebook RR3 Trackside: