M3

M3 is a designation used in several fields for distinct concepts. The most widely known is the BMW M3, a high-performance variant of the 3 Series produced since 1985. It began as the E30 M3 designed to homologate a racing engine and has since spanned multiple generations (E36, E46, E90/E92/E93, F80, G80), typically featuring a high-output engine, a performance-focused chassis, and sport-oriented equipment.

The M3 also refers to a motorway designation in road networks, with the best-known example being the M3 motorway in the United Kingdom, a link between the M25 near London and Southampton. Similar “M3” designations exist for other national road networks to denote major routes.

In biology, M3 denotes the muscarinic acetylcholine receptor subtype M3 (CHRM3), a G protein-coupled receptor expressed in smooth muscle and glands. Its activation triggers secretion and contraction, making it a target for various drugs used in conditions such as overactive bladder and COPD.

In music theory, M3 denotes a major third interval, spanning four semitones, and is a fundamental building block of chords and melodic structure.

In monetary statistics, M3 was a broad money supply measure used by some central banks, combining M2 with large time deposits and other near-money assets. It has largely been discontinued in official reporting but remains referenced in historical economic analysis.