In the United States, automakers quote power in terms of SAE net horsepower in accordance with SAE standard J1349. SAE Net horsepower is measured at the engine's crankshaft, and does not account for transmission losses. The SAE net power testing protocol calls for standard production-type belt-driven accessories, air cleaner, emission controls, exhaust system, and other power-consuming accessories. This produces ratings in closer alignment with the power produced by the engine as it is actually configured and sold.
It is my understanding, the standard adjustment for these accessory loads is 7hp. US spec cars are almost always listed as 7hp lower than their European counterparts due to the required accessory load.