I think the speed is 162. I'm going to try it right now had to buy one though but the reward is worth it.
As someone suggested, use the GT-R Spec-V and buy the power option to bring it to 492 BHP and get a custom FC tranny.
Tune the tranny to 168 MPH top speed.
Is all of this with default setup except for 168 - 162 top speed?
I wish this was repeatable, but then again it'd be too easy to get rich and lvl up.
Omg i did oil change and it autosaved!!! NOOOO!!! I have no more money.
Had to sell the unused GTR SPECV for 47,000 and grinding to make the money again....
Well ... that sucked. I got all other events in 1st try, and for this used a prize R32, modded it to 491HP and 1195kg suspension and tranny and everything. And I just can't get below 1:31 in lap times ... will try with a GT-R now, since I've read what everybody else has written ... it is silly to me, that a GT-R would be actually that much faster ...