BMW M56

The BMW M56 was a 2.5 litre, 184 PS straight-six engine, a re-engineered version of the M54B25 built to meet SULEV emissions rules in US states until 2006. The M56B25 was produced between 2002 and 2006 and was the first BMW Super Ultra Low Emission Vehicle engine, with the same power and vehicle performance as the comparable M54B25 car. It was fitted to the 325iA in the E46 sedan, coupe and sport wagon from 2003 to 2006, and was sold only in California, New York and Massachusetts, then Vermont from the 2004 model year. To meet the standard it uses dual downstream and warm-up catalytic converters, wide-band oxygen sensors, four-hole fuel injectors at 5 bar, VANOS set to a fixed position during start-up, a secondary air system, a stainless steel fuel system and a Direct Ozone Reduction System coating on the radiator. The N54 replaced it.