E30: the homologation origin
The first M3 arrived in 1986 as a basis for touring-car competition. Its four-cylinder engine and widened body set it apart from a regular E30. The cover photograph is an actual E30 M3, not another BMW series.
E36 and E46: the straight-six era
The E36 M3 began in 1992 and moved to a straight-six engine. The E46 M3 continued that approach in 2000, with the lightweight CSL taking a special place in its story. A regular E46 does not become an M3 through bodywork or badges.
E9x: the only V8 M3
The M3 generation introduced in 2007 used a naturally aspirated V8. Saloon, coupé and convertible have different chassis codes, so a specific car should be identified by its exact body style.
F80 and G80: turbocharging and new formats
The F80 M3 returned to a straight-six, now turbocharged, while the coupé and convertible became the M4. The next family added M xDrive and an estate: G80 identifies the saloon, while the M3 Touring is G81.