One of the most talked about cars on the Need for Speed World forums was the Pagani Huayra.
However, everytime a topic on this particular car was started or even a decent discussion was gaining momentum, one of the moderators would come along, cite the no discussing unreleased cars line and lock the thread down.
Now, thanks to that group of folks who put in the time to make World Offline, we can see a great answer to the mystery. Within the client, all the cars are there, including never released to the public models. In the case of Pagani, either the Huayra was never completed before the original developer team was let go, or the car was cancelled from the game. So, it wasn't a matter of an unreleased car, but a non-existent one.
No doubt one of those moderators would love to flex their muscles here, but too bad, this is my house, you have no power to abuse here.
Over in Forza 6 Apex, I just recently unlocked the Pagani Huayra and was itching to try it out. Here is that first run https://www.youtube.com/watch?v=iEEF3zObXmI
Looking back, not ever seeing the Pagani Huayra in Need for Speed World is both a shame and a blessing, I suppose. The shame is the car wasn't put into the game for players to enjoy and depending if it was available for SpeedBoost, would have meant some real world money in EA's pocket.
The blessing part comes from the very fact the car never made it into the game, just another memory to either try and relive or flatout forget.