I still cannot understand why Ferrari creates such terrific vehicles but rarely provides them for comparisons. Also, why are publications banned from testing customer's cars for comparisons?

Autocar's recent comparison of the Porsche 918 and McLaren P1 illustrates this sad fact perfectly:

Why no LaFerrari?

There was one simple reason for the absence of Ferrari's rival hypercar here: Maranello was invited to provide a car for this test but declined. At the same time, Ferrari made it clear that were we to test a private example, we would not be invited back to Maranello any time soon. Which is a shame because, having driven all three, albeit on separate occasions, I'm reasonably certain that LaFerrari would, shall we say, have acquitted itself quite well in this contest. But there you go…