In the 1970's the SAE (Society of Automotive Engineers) imposed standard tests on American manufacturers, which improved comparative values. However, they are still allowed to test their engines in different ways. The SAE J1349 Engine Power Test Code specifies a net power, measured by a dynamometer. The basis of the current test is about thirty years old, and the last "adaptation" dates from 1995, so that the manufacturers still provide higher values than the actual power and torque. In 2004 finally a uniform SAE standard arrived.
In Europe, the DIN (Deutsche Industrie Norm) 70020 and DIN 6270 were accepted, and they impose a measurement of the engine's power with ALL fixed accessories, such as inlet and outlet, fan, water, fuel and injection pump, and no alternator.
