BMW 3 Series: 40 years old, and still the ultimate driving machine

BMW’s sector-defining 3 Series has turned 40, so the start of the story is in 1975—except it isn’t. You have to go back much further: past the early '70s when work began on the first 3 Series, and even back beyond the 1966 predecessor that set the pattern for compact BMWs. You have to reverse all the way back to 1959.

In the 1950s, BMW’s curiously bipolar range of cars had grand, expensive "Baroque Angel" saloons at one end, tiny two-cylinder BMW Isetta bubble cars at the other, and almost nothing in between. In 1959, German industrialists Harald and Herbert Quandt took control of the company and gave it the cash injection it needed to create a new medium-size saloon, the 1961 Neue Klasse (new class).

With monocoque construction, independent suspension, and peppy overhead cam engines, the Neue Klasse sold well and quickly spawned both larger-engined derivatives and a smaller, cheaper car based on the same engines and running gear. The two-door 1.6-litre 1600-2 arrived in 1966, followed in 1968 by the definitive 2.0L 2002. More than 800,000 were built in the 1960s and 1970s, and they established a blend of compact size, tidy handling and swift performance which would become the cornerstone of the 3 Series' appeal.

E21: 1975-1981

The triple challenge of emissions, safety, and customer expectation shaped its successor, known internally as the E21 (E for Entwicklung—development in English) and everywhere else as the 3 Series. The new bodyshell was longer and heavier, but also stiffer and safer, with crumple zones and a better-protected fuel tank. Tidy styling echoed the 1972 E12 5 Series, and the interior also owed much to the E12 but added, literally, a new twist: the centre section of the dashboard was angled toward the driver in what BMW called a "cockpit style" layout.

Under the skin the E21 mixed new and old, with MacPherson strut front suspension and semi-trailing arms at the rear like the ’02, but crisp ZF Gemmer rack and pinion steering replacing the old steering box. Initially the engines were all developments of the M115 (later redesignated M10) unit of the Neue Klasse, ranging from 1.6 to 2.0 litres. In 1977, a new M60 in-line six was introduced, upgrading the 320 and Bosch-injected 320i to six-cylinder smoothness and paving the way for a swift 143hp 2.3-litre 323i range-topper early in 1978.

It all added up to an attractive, comfortable, covetable car with excellent performance and economy. BMW had built 1.36 million E21s by the time production ended late in 1982, but the car that replaced the E21 was to be even more successful.

E30: 1982-1991

Key to the broader appeal of the E30, the second-generation 3 Series, was a wider range of models. The two-door saloon was joined by a four-door, then a convertible and a Touring estate. There was also a wider range of engines: six-cylinder diesels were available for the first time, and the petrol engines ranged from 1.6-litre fours to a creamy-smooth 2.5-litre injection six. The early 1980s oil crisis also prompted an economy 325e, with a low-friction, low-revving 2.7-litre six. E30s retained the semi-trailing arm rear end of the E21, which easily gave up its grip if provoked, leading to lurid tail slides. But overall it was efficient, well-built, oozed success and upward mobility, and proved an effective rival for the new compact Mercedes-Benz 190.

E36: 1992-1999

The E36 third-generation 3 Series was bigger, quieter, and introduced an aerodynamic new shape with flush glazing. The core model was now the four-door saloon, with the two-door reinvented as a stylish coupé. Semi-trailing arm rear suspension (a BMW favourite since the 1960s) had finally gone, and in its place came a multi-link system called the "Z-axle." But not every E36 customer benefited from the more secure handling this generated: a new three-door hatchback 3 Series called the Compact retained the old semi-trailing arms, supposedly because they intruded less on luggage space.

An even wider range of engines was available: all the petrol units were now fuel injected, there were four-cylinder and six-cylinder turbodiesels, and a new 24-valve straight six for a more refined M3. BMW didn't originally sell the E36 M3 in the US because the E30 M3 hadn't sold very well over there. Eventually, following a letter-writing campaign organised by the BMW Car Club of America, BMW released the E36 M3 in North America in 1994—but to keep costs down (to hopefully encourage sales) the North American version had a weaker engine than the European-spec M3 (283hp vs. 240hp).

Like its predecessors, the E36 won over private buyers with its quality image, and fleets with its low depreciation. But it wasn’t perfect: the electro-hydraulic SMG gearbox option on the M3 was clever but widely disliked, trim durability was poor, and there was a string of engine failures due to wear of Nikasil cylinder walls (a problem other car makers shared).

E46: 1998-2006

In the mid-1990s, BMW began developing the fourth-generation 3 Series, the E46. Slightly longer and wider than the E36, it offered better accommodation inside while protecting occupants with a stronger, stiffer body, and a range of secondary safety systems: safety was becoming a much bigger factor in new car choices. The engine was mounted farther back, giving 50-50 weight distribution which improved the handling still further. Power was largely provided by six-cylinder engines, though there were still entry-level petrol and diesel fours. The M3 had a mighty 3.2-litre six, which punched out 338hp if you revved it just shy of its 8000rpm limiter, connected to Getrag six-speed gearboxes with manual or improved SMG II electro-hydraulic control.

E9x: 2005-2011

The next-generation M3 was even more powerful, but as always the mainstream 3 Series models arrived first. The E9x (E90 four-door, E91 Touring estate, E92 two-door) brought greater refinement and even better crash performance. After the evolutionary E46, the E9x was stuffed with innovations, not all of them entirely successful. The new infotainment system, with rotary iDrive controller on the centre console, wasn’t popular, and the runflat tyres offered safety gains at the expense of ride quality. The edgy "flame surfaced" styling was controversial too, though the convertible’s move from a folding fabric roof to a retractable hardtop was welcomed.

The M3 adopted the high-revving S65 V8 engine (414hp at 8300rpm) and provided even swifter performance than before, with a spine-tingling soundtrack. Mainstream 3 Series buyers were treated to some clever engineering, too: the 320d EfficientDynamics offered excellent fuel economy with the same real-world performance as a regular 320d thanks to longer gearing, a retuned engine and aerodynamic refinements.

F30 & F31: 2012-

The sixth-generation 3 Series, which was unveiled in 2011, was reduced to just saloon (F30) and Touring (F31) body styles—the coupé was now renamed 4 Series (internally named the F32). BMW invested €500 million (£365 million) in its Munich plant to build the sixth-gen 3 Series; centrepiece was a new 2500-tonne body panel press which could work at 17 cycles a minute, processing 600 tonnes of steel a day. (That's enough to build the Eiffel Tower in just 12 days, in case you ever wondered.)

Laser welding and bonding replaced some of the conventional spot welding, improving body sealing and corrosion prevention. It made the new 3’s body stiffer, too, despite it being 45kg lighter than the old car. Sound deadening was improved by injecting foam insulation into cavities between the engine bay and passenger cell. Improving the production process had other benefits: BMW claimed the non-recyclable waste from the manufacture of each vehicle weighed just eight grams.

The four launch engines were all TwinPower Turbo units, any of which could be mated to an eight-speed automatic gearbox—the first in its segment, and efficient enough to beat the six-speed manual in fuel consumption and emissions testing. Another first for the sector was a full-colour head-up display, and a parking assistance system with a "top view" (bird's-eye view) function. The ActiveHybrid 3 of 2012 was the first hybrid 3 Series, its 40kW electric motor designed to improve acceleration without fuel consumption penalty. A new bodystyle, the five-door fastback GT, was added in 2013.

There was less obvious cleverness, too, like the vents at the front of the car which accelerated air through and out of the wheel wells. This "air curtain" reduced aerodynamic drag, helping the F30 record a notably slippery drag coefficient of 0.26.

The latest M3 gives up the previous generations’ high-revving, normally-aspirated engines for a downsized twin-turbo straight six, and arguably loses some character in the process. But it has a little more power, a lot more torque, and is significantly swifter and more fuel-efficient than the car it replaces.

The F30 is a fine example of what BMW's four-decade 3 Series strategy ultimately boils down to: never too radical, but never old-fashioned, while using the best current technology to make a premium product ever better. And BMW needs to keep improving: today, the 3 Series faces the strongest challengers it has ever seen, including Jaguar’s brilliant new XE, Audi’s advanced B9-generation A4, and soon a facelifted Mercedes-Benz C Class.

With updated styling and new engines—including the 1.5-litre three-cylinder turbo petrol from the Mini and 2 Series—the 3 Series has every chance of keeping its spot as the world’s favourite premium car.

Andrew Noakes is a freelance motoring writer, photographer, and lecturer. He has written for most major UK motoring magazines, and penned books about the history of Mercedes, BMW, and Aston Martin. When he's not writing or driving, Andrew teaches on Automotive Journalism at Coventry University and sits as the deputy chairman of the Guild of Motoring Writers.