The BMW E21 was the original BMW 3-Series automobile, produced from 1975 to 1983. It replaced the BMW 2002 and was succeeded by the BMW E30. Worldwide sales of the E21 topped 1.36 million, although the car was not particularly popular in the lucrative United States market.

For the driving enthusiast the pick of the crop was most certainly the 323i, a car widely credited with being the first executive-sporting car. Previously, the British motor industry had come close to cracking the formula, producing cars such as Rover's P5 (too soft for a sports car) and Triumph's Dolomite (too raw as an executive). Had they moved their designs in just the right direction they could still be producing cars today. As it stands the combination of strong build quality, straight six power and, perhaps most importantly, rear-wheel drive, proved just the ticket for thrusting young executives needing the right combination of image and involvement until they could afford a 911.

Under the direction of a new 51% percent shareholder, Gunther Quandt, BMW decided upon a replacement for their ageing 2002 (a car very reminiscent of the Dolomite, and a classic in its own right). It would serve as the entry level model in a four-pronged attack on Mercedes-Benz also consisting of the larger 5, 6, and 7-series BMWs. It became known as the now ubiquitous 3-series, and the 323i would be it's halo car. Without it, there was the distinct possibility of BMW moving from its core mission of building ultimate driving machines and in doing so alienating an existing customer base long enamoured with the charms of the smaller 2002.

Handling was not the issue for the 3 series. With independent suspension all-round, four-wheel disc brakes and superbly communicative steering this was a modern chassis in the best of teutonic tradition. What enthusiasts called out for was more power. A modern engine that had to meet the demands of a new era of traffic jams, emissions legislation and oil crises, while still providing a real incentive to just go out and drive the thing. In looking for a designer, they could scarcely have done better than to employ the services of Paul Rosche. Rosche, a BMW engineer from 1957 through to his retirement in 1999, already had such iconic engines as the 286hp 6 cylinder of the M1 and the 2litre motor of the 2002 turbo (famously, one of the most politically incorrect cars of all time) to his name. Rosche settled upon a 2.3litre straight six, the largest capacity engine that would fit in the compact engine bay, the first cylinder nestling almost beneath the dashboard. While the power it produced was more than adequate (143bhp and 145lb ft of torque) for the 1100kg car, it was the delivery that made the engine such a fantastic companion to work with. Turbine smooth and with a rich swell of torque that kept you entertained until the real fireworks began at 3600rpm, the engine delighted in being rung right out to its seemingly conservative 6500rpm redline. With a now classic BMW straight-six soundtrack, this was the engine that brought the highest pedigree of motoring engineering to, if not every motorist, then at least the upper-middle class.

In 1983 the E21 evolved into the even more accomplished E30, and when that became the E36 in 1992, BMW for the first time sold more cars in a calender year than Mercedes-Benz. The 3 series' place in automotive history was sealed. Today the market segment the 3 series created is absolutely littered with competitors. Fittingly, it is a segment the 3 series continues to dominate.

Variants

BMW 320 (1977 - 1982)

• 315: The most economical model, introduced to the market in reaction to the second "oil crisis" in late 1979, with a 4-cylinder M10 1.6L engine and a single downdraft carburetor, 75 hp. More spartan than the other E21 models, it was the last E21 to be built and shared production with the E30.
• 316: The original 3-series base model with M10 1.8L engine, 90 hp.
• 318: Slightly more powerful version (98 hp) with 1.8L engine.
• 318i: An upgraded version of the 316 featuring the M10 1.8L engine fitted with a Bosch fuel injection system, introduced in 1979 as successor to the carburetted 318.
• 320: Featured an M10 four-cylinder engine with a Solex 2-barrel downdraft carburetor, 109 hp.
• 320i: Upgraded version of 320 with an M10 engine; Bosch K Jetronic fuel injection, 125 hp.
• 320/6: Featured the new BMW 6 cylinder engine, the M20 2.0L, and a Solex 4-barrel downdraft carburetor; replaced the 320/4 from 1979 on.
• 323i: Featuring the M20 and Bosch K jetronic fuel injection, the 323i was the top model of the line, 143 hp, and replaced the 320i from 1979 on.

In non-USA markets, the 316/318/318i models were marked by single headlights, while the more upscale 320/323i models featured quad headlights.

The 320i was available in the United States market and was remarkably different from the European models. Department of Transportation (DOT) safety regulations required larger bumpers, different headlight sets, and DOT marker lamps on the sides. It was a basic car, a radio was not even an option, nor was power steering.

Companies such as Hartge, Alpina and AC Schnitzer offered aftermarket modifications for the E21.

A cabriolet conversion was offered by Karrosserie Baur GmbH, based on regular E21 models. The cabriolet conversion was composed of a targa roof and an independent rear soft top. Production of the Baur TopCabriolet began in 1978, and were sold via the BMW dealership network. All TopCabriolets included the BMW warranty. A total of 4,595 vehicles were manufactured before production ended in 1981.

• United Bimmer is a BMW community offering a support forum for e21 owners, a wallpaper gallery, and many other BMW resources.