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

Focusing on driving dynamics and technology has kept BMW at the top for six generations.

The BMW 3 Series throughout the ages, with the F30 and E21 in the foreground.

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   The BMW 3 Series throughout the ages, with the F30 and E21 in the foreground.
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   3 Series profiles, throughout the ages. Here, the E21.
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   3 Series profiles, throughout the ages. Here, the E30.
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   3 Series profiles, throughout the ages. Here, the E36.
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   3 Series profiles, throughout the ages. Here, the E46.
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   3 Series profiles, throughout the ages. Here, the E90.
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   3 Series profiles, throughout the ages. Here, the F30.
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   3 Series grilles, throughout the ages.
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   3 Series grilles, throughout the ages.
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    3 Series grilles, throughout the ages.
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    3 Series grilles, throughout the ages.
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    3 Series grilles, throughout the ages.
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    3 Series grilles, throughout the ages.
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    3 Series rear lights, throughout the ages.
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    3 Series rear lights, throughout the ages.
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    3 Series rear lights, throughout the ages.
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    3 Series rear lights, throughout the ages.
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    3 Series rear lights, throughout the ages.
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    3 Series rear lights, throughout the ages.

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.

Further Reading

Porsche 911: 52 years of staying true to its roots

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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.

The E30 M3 was a huge success in saloon car racing. This is Marc Hessel at the Norisring in 1987 – he almost won the DTM championship that year.

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   The E30 M3 was a huge success in saloon car racing. This is Marc Hessel at the Norisring in 1987 – he almost won the DTM championship that year.
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   Bernard Beguin won the 1987 Tour de Corse rally in an E30 M3.
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   E21 styling owed much to the earlier E12 5 Series.
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   E30 M3 Sport Evolution engine developed 234hp.
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   E30 M3 engine produced 197bhp in original form – not a huge output by modern standards.
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   E30 M3 engine used the same M10 block that underpinned BMW’s turbo F1 engines, with a cylinder head related to that developed for CSL endurance racers.
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   Road and race M3s compared: the tuned race engines were good for 300bhp from just 2.3 normally-aspirated litres.
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   Highlights from the evolution of BMW’s range seen in 2002, with E21 (front left), E30 (back), E36 Compact (far left) plus the 2002 (orange) and ‘Neue Klasse’ 2000 (far right).
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   E30 M3 Sport Evolution added some aero tweaks and more power.
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    E30 M3 in action. All the cars were left-hand drive, even those brought to the UK.
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    E30 M3 had a higher boot line and different rear window slope from other E30s to improve aerodynamics.
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    E30 M3 is an all-time classic – an exciting road car and a dominant saloon-car racer.
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    Diesel engines were introduced with the E30 and became a popular option.
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    E30 extended the 3 Series appeal by adding a four-door saloon body, and later a Touring estate.
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    Black panel between E21 rear lights was a last-minute addition to spruce up the rear-end view.
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    First generation 3 Series was known internally as E21.
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    E21 was only available in one bodystyle – a two-door saloon.
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    E30 looks boxy to modern eyes, but aerodynamic efficiency was becoming important even in the early 1980s – note the black air dam.
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    E30 had handsome square-cut looks, and offered high quality in a compact package.
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    E30 M3 cabriolet shows off its extended arches in this view.
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    The E30 M3 was also available in cabriolet form.
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    Note the extended air dam and rear aerofoil on the M3 Sport Evolution.

Made for Motorsport

Established in 1972, BMW Motorsport built competition cars and one-off special road cars, then established a line of M-badged performance versions of BMW’s road car range. In 1985 it created a high-performance E30, the M3.
At its heart was a new 2.3-litre, four-cylinder engine based on the venerable but tough M10 block. This was allied to a 16-valve cylinder head, itself based on the 24-valve head developed for racing BMW CSLs and subsequently used on the M1 supercar, M5, and M635CSi. The new motor produced 200bhp at 6700rpm—not immense by modern standards, but 15 percent more than the contemporary 325i and with plenty of development potential for racing. The M3 was given a close-ratio Getrag gearbox, quicker steering, and a ZF limited-slip differential. The wider arches, deep front air dam, and boot-mounted wing, were joined by a higher boot lid and repositioned rear window to improve the aerodynamics.
It was an exciting road car, and as a racer it dominated touring car championships around the world. It also began a line of M3 models which continues to this day, though all the M3s which followed were focussed on road performance rather than track competitiveness.

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).

Bodies Beautiful

Chart the number of body styles offered within the 3 Series over the years and you get a bell curve. The first-generation E21 had only one mainstream body, a two-door saloon, though there was also a rare targa-top conversion by German coachbuilder Baur. The E30 was also available as a two-door saloon, and Baur continued to build cabriolets, but the mainstream BMW range added a four-door body, an elegant full convertible, a rather cramped Touring estate, and the very specialised M3.
For the third-generation 3 Series, the E36, BMW added another new body style: the Compact. This short-tailed three-door, which retained the now outmoded semi-trailing arm suspension of the E30, echoed the three-door Touring version of the ’02 Series built two decades before and was intended to steal sales from the burgeoning hot hatch market. It never really appealed to its intended audience and didn’t reappear in future 3 Series generations.
The E46 and E9x both appeared in two-door, four-door, convertible, and Touring forms, but the F30 marked a departure: the two-door coupé was now marketed as a 4 Series, while the 3 Series gained a five-door GT variant. There was also a long-wheelbase version for the legroom-crazy Chinese market.

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.

E36 introduced flush glazing to reduce drag, and a sophisticated new independent rear suspension system.

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   E36 introduced flush glazing to reduce drag, and a sophisticated new independent rear suspension system.
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   E36 was available with two or four doors and as a cabriolet. There was also a Touring estate and a three-door Compact hatchback.
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   E36 3 Series was bigger and more aerodynamically efficient.
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   Four-door E36 was the default compact executive car of the 1990s.
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   E46 M3 provided an extraordinary blend of pace, handling and refinement.
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   E46 facelift included reshaped front lights and indicators – though the M3 models retained the old-style lights.
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   Weight distribution was improved on the E46 3 Series, giving even better handling.
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   Bodyshell of the E46 3 Series was stronger and stiffer, providing greater crash protection.
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   E46 CSL engine was still 3.2 litres like the regular M3, but produced 355bhp – up 17bhp thanks to a carbon airbox, revised cams and valves, and a new exhaust system.
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    F3x 3 Series models continue the evolution of BMW’s style, but retains key features like the twin "kidney" grille and the "Hofmeister kink" in the rear side window.
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    Concept sketch of the latest 3 Series is close to the production car’s shape.
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    Another concept sketch. The grille shape has been a BMW feature as far back as the 1930s.
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    Latest 3 Series (front) with its forebears – from right, E21, E30, E36, E46, E92.
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    All the current 3 Series engines are from BMW’s TwinPower Turbo family – this is the diesel.
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    3 Series petrol engines are also turbocharged. The intake charge intercooler at the front improves efficiency and reliability.
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    3 Series interior still provides a great driving environment, though the "cockpit style" of the old cars has been toned down.
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    Latest 3 Series cars are available with ZF’s 8HP 8-speed automatic transmission.
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    3 Series in production at BMW’s Munich plant. Munich production plant had a €500 million upgrade in preparation for the latest-generation car.
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    Much of the process is automated, but there is still a place for human skill such as in these quality checks.
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    Production is laid out over 700,000 square feet and five floors of the Munich facility.
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    Car is raised to a comfortable height for each operation, and machines assist operators to reduce fatigue – improving production efficiency and quality.
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    After painting the bodyshell is baked in an oven to cure the paint.
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    Wheels go on near the end of production. Each car has a computerised build record to ensure the right components are used from the many different specifications and options.
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    Jig rotates the body for work underneath.
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    Interior designer Christian Bauer with a clay model of the 3 Series interior.
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    The finished clay model is covered with a film which simulates painted metal, so the design can be judged against other cars.
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    Designers use a wide range of rendering techniques, from biros on paper to interactive pen displays.
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    Even with sophisticated 3D modelling techniques available, car designers still produce full-size clay models.
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    Christopher Weil was one of the designers responsible for the latest 3 Series’ exterior design.
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    Alternative 3 Series interior concept.
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    Concept sketch for the 3 Series interior.

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.)

Transmission Revamps

Four-speed manual gearboxes were the norm in 1975, but the E21 could also have a five-speed manual with an overdrive top gear for quieter cruising, or a direct-top five-speed with closer-stacked intermediate ratios for better acceleration. There was also the option of a ZF three-speed automatic, which introduced clutches rather than brake bands to control ratio selection, improving smoothness.
A four-speed ZF automatic with a lock-up clutch to improve cruise fuel economy was introduced on the E30, and on the E36 driver-selectable Sport, Economy and Winter modes were added. The E36 M3 could also be had with a new electro-hydraulically operated manual box, SMG. On the E46, four- and five-speed automatics communicated with the engine management system via the car’s controller area network (CAN) bus for smoother gear changes. The M3 was upgraded to SMG II, and a cheaper, simpler sequential system called SSG was offered on lesser models.
At the same time, a new technology was on the horizon—the dual-clutch transmission, or DCT—and this took over on the E9x generation M3. The latest F30 3 Series still offers manuals (now six-speeders), conventional automatics (with predictive shifting based on sat-nav data), and the M-DCT dual clutch in the M3.

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.
This post originated on Ars Technica UK