This manual covers the 1990 BMW 3 Series (E30) and M3 (E30) models, equipped with M20B25 or M20B27 engines for the 325i/is/e/es variants and the S14 engine for the M3. These vehicles are renowned for their sporty handling, driver-focused engineering, and robust inline-six and performance four-cylinder engines, embodying BMW's legacy of producing engaging driving machines. The E30 generation, produced from 1982 to 1994, represents a significant period in BMW's history, with the 1990 models benefiting from evolutionary improvements. The M3 variant, in particular, stands out as a homologation special derived from motorsport, celebrated for its exceptional performance and iconic status.

This comprehensive service and repair manual provides factory-level detail for all aspects of the 1990 BMW 3 Series and M3. It includes in-depth procedures for powertrain, drivetrain, chassis, electrical, and body systems, covering everything from routine maintenance and scheduled service intervals to complex diagnostics and major component overhauls. Essential information such as torque specifications, fluid types, capacities, and troubleshooting flowcharts is readily available. This manual is an indispensable resource for professional BMW technicians, independent repair shops, and dedicated enthusiasts seeking to maintain, repair, and preserve the integrity and performance of these classic vehicles.