The STO is a special version of the Huracan, It’s Lamborghini’s most track-attack Huracán ever, descended from the DNA of the Super Trofeo race cars – hence the ‘STO’ name (Super Trofeo Omologata) – and a road car that Lamborghini thinks is more biased toward a circuit than a street. 
The STO is a rear-drive only Huracán that’s 43kg lighter than the Huracán Performante, it has a shark fin that apparently keeps the air straight over the (manually adjustable) rear wing, and aids stability during high-speed excessiveness. The whole front end of the Huracan STO, called the “cofango” by Lamborghini, is one piece that consists of the fenders, hood, and bumper.