First everyone thought the Adder was the best car because it's based on a Bugatti. Then people realized the Entity XF is faster and everyone started having one (Which is considerably ironic taking in account the car's name). And now, since the Turismo is the 2nd fastest car in the game, it has become the latest trend.
Prediction: The same will happen with the Zentorno.
The entity isn't faster, do a drag race you'll soon see.