The BMW 3 Series is an entry-level luxury car/compact executive car manufactured by the German automaker BMW since May 1975. Successor to the 2002 coupe, it has been produced in five different generations and in no less than five different body styles. It is BMW's best selling automobile, accounting for nearly 40% of the company's auto sales in 2005.

BMW released its E21 in the wake of the 1973 oil crisis, attracting customers seeking both prestige and economy, nearly doubling BMW's worldwide auto sales figures in three years, and winning numerous automotive world awards and honors. Three decades later, the 3 Series' E46 was the best-selling of its class,as commonplace in Asia and America as in Europe, while maintaining its prestigious brand and image.

The 3 series has also maintained BMW's racing heritage. The M version of the 3 series, M3, debuted in the 1980. Marketed as a daily driver and a track ready race car, M3's popularity as a sports sedan raised customer awareness of the 3 series brand.[citation needed]

3 Series vehicles can be largely differentiated by the underlying platform:

• BMW E21 - (1975–1983) 3 Series
• BMW E30 - (1984–1994) 3 Series
• BMW E36 - (1992–1998) 3 Series
• BMW E46 - (1999–2006) 3 Series
• BMW E90 - (2005–) 3 Series Sedan
• BMW E91 - (2006-) 3 Series Wagon
• BMW E92 - (2007-) 3 Series Coupé
• BMW E93 - (2007-) 3 Series Convertible

Main article: BMW E21

The E21 line was produced from May 2, 1975 (1977 in the USA) through 1983. Originally a replacement for the 2002 coupe, the first 3-Series was a 2-door model only. The New Class sedans would be replaced by the 5 Series. A factory authorised cabrio version was built by Baur.

Models:

• for Europe
  • 1981-1983 315 - 1.6L M41 I4, 75PS (55kW)
  • 1975-1979 316 - 1.6L M41 I4, 90PS (66kW)
  • 1980-1983 316 - 1.8L M10B18 I4, 90PS (66kW)
  • 1975-1980 318 - 1.8L M42 I4, 98PS (72kW)
  • 1979-1983 318i - 1.8L M42 I4, 105PS (77kW)
  • 1975-1979 320/4 - 2.0L M64 I4, 109PS (80kW)
  • 1975-1979 320i - 2.0L M10B20 I4, 125PS (92kW)
  • 1979-1982 320/6 - 2.0L M20B20 I6, 122PS (90kW)
  • 1978-1982 323i - 2.3L M20B23 I6, 143PS (105kW)
• for the rest of world
  • 1976-1979 320i - 2.0L M43/1 I4, 110hp (82kW)
  • 1980-1983 320i - 1.8L M42 I4, 100hp (75kW)

Main article: BMW E30

The E30 was sold from 1982 through 1991 in sedan form, through 1993 in convertible form. The E30's introductory price of US$18,210 was nearly double that of the E21 just 7 years earlier, but the availability of a six cylinder engine and 4-door body style (in 1984) earned sales. The torquey "eta" six in the 325e produced 121hp (90kW), but met the strict emission standards of the time. The E30 was the most powerful compact BMW offered in the United States since the 2002 Tii.