BMW 5 Series (E12)

The BMW E12 is the first generation of 5 Series executive cars, which was produced from 1972 to 1981 and replaced the saloon models of the BMW New Class range.

Initial models were powered by inline-four engines, using either a carburettor or fuel-injection. A year after launch, the first model powered by a straight-six engine was introduced. By the final years of E12 production, most models used a straight-six engine.

There was no M5 model for the E12, however the E12 M535i is considered to be the predecessor to the M5. The E24 6 Series coupés were built on the E12 platform up until 1982. The E12 was replaced by the E28 5 Series in 1981, although the tools were sent to South Africa where E12 assembly continued (with E28 interiors) until 1984.

Development

left|thumb|BMW 2200ti Garmisch (replica)

At the 1970 Geneva Motor Show, BMW unveiled the 2200ti Garmisch concept car, a 2-door saloon which was developed in conjunction with Bertone. The 2200ti Garmisch concept car was shown as a potential replacement for the New Class saloons and the eventual E12 production model utilized many design elements from the Garmisch.

Development of the E12-series had begun by the end of the 1960s, when wind tunnel tests were conducted. Eberhard von Kuenheim, then chairman of BMW's supervisory board, hired French designer Paul Bracq in 1970 to work as the E12's Chief of design, with Marcello Gandini of Bertone as co-designers of the exterior.

In 1971, a road-legal E12 prototype, which looked similar to a Fiat 132, was made. Also in 1971, Paul Bracq had finalised the E12's design, however, compared with the later series production E12, Bracq's design car had a more stretched, and dynamic appearance. Computers were used in BMW development for the first time to calculate front and rear crumple zones; the roof was designed with a rollover protection structure. The body has a drag coefficient of 0.44.

Before the E12 had been introduced, there were rumours that it would be available with both a 2.2 litre four-cylinder engine, and a small six-cylinder engine. With the introduction of the E12-series in 1972, BMW offered two models, the carburetted 520, which had a Stromberg constant pressure carburettor, and the manifold injected 520i, which came with a Kugelfischer PL 04 injection pump. A small six-cylinder model called "523" had been developed, but was never put into series production. Eventually, a small six-cylinder model was put into production in 1977, but in the 2-litre "520" version rather than a 2.3 litre version.

Originally, four-cylinder cars have a bonnet with a sunken central portion whereas on six-cylinder cars this section is raised. The leading edge of the bonnet was flat. After the August 1976 facelift all models featured the same bonnet, with a narrow raised central section reaching all the way forward and wrapping around the "kidneys". M30-engined cars can be identified by the grille having a chrome surround.

To meet Sweden's unique and stringent emissions standards, a fuel injected version of the 528 was developed and entered production in June 1977. Called the 528i, this was successful enough that it replaced the 528 in most markets.

BMW E12 520i, rear (cropped).jpg|Rear view, until 1976

File:BMW520 1978 white.jpg |Rear view, after facelift

File:BMW E12 Interior.jpg |Interior

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Engines

{|class="wikitable sortable"

! Model !! Engine !! Power !! Torque !! Years

| 518 || 1.8 L M118 straight-4 || at 5,500 rpm || at 3,500 rpm || 1974–1981

| 520 || 2.0 L M17 straight-4 || at 5,800 rpm || at 3,700 rpm || 1972–1977

| rowspan="2" | 520i || rowspan="2" | 2.0 L M64 straight-4 || at 5,800 rpm || at 4,500 rpm || 1972–1975

| at 5,700 rpm || at 4,350 rpm || 1975–1977

| 520/6 || 2.0 L M20B20 straight-6 || at 6,000 rpm || at 4,000 rpm || 1976–1981

| rowspan="2" | 525 || rowspan="2" | 2.5 L M30B25 straight-6 || at 6,000 rpm || at 3,700 rpm || 1973–1976

| at 5,800 rpm || at 4,000 rpm || 1976–1981

| rowspan="2" | 528 || rowspan="2" | 2.8 L M30B28 straight-6 || at 5,800 rpm || at 4,000 rpm || 1974–1976

| at 5,800 rpm || at 4,000 rpm || 1976–1978

| rowspan="3" | 528i || rowspan="3" | 2.8 L M30B28 straight-6 || at 5,800 rpm

| M535i || 3.5 L M90 straight-6 || at 5,200 rpm || at 4,000 rpm || 1980–1981

M10 inline-four engine|thumb|right

The data above are manufacturer claims. Power and torque data is measured according to the German Standard DIN 70020.

The 518, 520 and 520i models were fitted with the 1.8 L and 2.0 L M10 inline-four engines, as per the previous New Class saloons. The 525, 528, 530, 530i and 533i models were fitted with M30 straight-six engines, as used in the New Six large saloons and E9 coupés. The 520 (and 523, which was developed but never put into series production) uses the M20 straight-six engine.

The 518 had its fuel supplied by a Solex 32/32 DIDTA carburetor, while the initial 520 model (powered by the M10 inline-four engine) used twin Stromberg 175CDET carburettors. The straight-six engine 525 and 528 models used dual Zenith INAT two-barrel carburettors up until the 1976 facelift. The straight-six 520 used a Solex 4A1 carburettor.

Fuel-injected models have the letter i at the end of their model designation. The 520i used the Kugelfischer mechanical fuel injection system from the 2000tii and 2002tii until 1975. From 1975, it was fitted with a mechanical continuous Bosch K-Jetronic port injection. The 518i (only sold in Sweden and Japan), 528i, and 530i (only sold in the US and Japan) have a Bosch L-Jetronic port injection.

Getrag 242 4-speed (for M10/M20/M30 engine models)
Getrag 262 4-speed (M30 engine)
ZF S4-18/3 4-speed (M30 engine)

The 5-speed manual transmission options consisted of:

Getrag 235 5-speed (M10 engine)
Getrag 245 5-speed (M10/M20 engines)
Getrag 265 5-speed (M30 engine)

The automatic transmission options—all 3-speed transmissions—consisted of:

ZF 3HP12 (M10 engine)
ZF 3HP20 (M30 engine)
ZF 3HP22 (M20/M30 engines)
BorgWarner BW65 (M30 engine)

Special models

On the Belgian and Greek markets, there was a BMW 518 Deluxe version. One thousand of these cars were sold in 1979–1980. This was a BMW 518 equipped as the 528i top model with additional luxury items such as headrests on the back seats. It was rumored that this special version was produced for the Iranian government, as a car for top officials under the shah's rule. Due to the Iranian revolution these cars were never delivered. Instead, they have been sold as a special version in Belgium and Greece.

The Portuguese market also received nearly 700 CKD units due to the local regulations that demanded a certain number of vehicles sold in Portugal to be locally assembled.

For the Swedish market the complete BMW 5 range was not offered, due to local emissions regulations. For the early E12 the models BMW 518, BMW 520, BMW 520i, and BMW 525 were offered - with the BMW 528 missing. The series 2 range of was reduced to three models: BMW 518i, BMW 520i and BMW 528i. the Motorsport 530i used the fuel-injected engine from the BMW 3.0Si and the Motorsport 533i used the injected 3.2-liter engine from the E24 633CSi. Other modifications were a shorter differential ratio of (3.45:1 for the 530 and 3.25:1 for the 530i),

M535i

thumb|M535i model at [[Concorso d'Eleganza Villa d'Este, Villa Erba 2022]]

The first M-badged 5 Series was the M535i, which began production in 1980. The M535i is powered by the M90 straight-six engine which produces . The sole gearbox choice is a 5-speed manual and 1,650 M535i cars were produced (including 240 CKD for South Africa). Features include optional front and rear spoilers, optional M-striping, sports suspension, Recaro sport seats, the steering wheel from the BMW M1, a dogleg close-ratio transmission, a limited-slip differential and larger brakes.

The M535i is considered to be the predecessor to the BMW M5 model, which has been produced since the E28 generation.

Alpina B7

thumb|Alpina B7 S Turbo

The Alpina B7 Turbo and B7 S Turbo were based on the E12.

530 MLE

In South Africa, the 530 MLE was produced as a homologation special for racing, with 218 cars produced. The engine is a M30, producing . Significant weight reduction measures were undertaken, included body panels made from aluminium or thinner steel.

Model year changes

1974

518 and 528 models introduced, producing and respectively.. Motorsport upgrades available as special order in 530, 530i or 533i guise.

1976 facelift

With the introduction of the E23 7 Series, the E12 received a facelift in September 1976. The styling was overseen by Claus Luthe. The rear-mounted gasoline filler door was relocated to the side of the car and the taillights were widened. The hood was redesigned to a give a 'power bulge' which accentuated the BMW kidney grille, and the dashboard ventilation was repositioned to improve air distribution.

As part of the facelift, the 520 model switched from the M10 inline-four engine to the BMW M20 straight-six engine, with the post-facelift 520 model often referred to as the 520/6. However, the M10 engine continued to be used in South Africa, due to local content laws. Even after the M20 entered local production in 1979, the 2.0-litre M10 continued to be available with "518" badges in South Africa. In other markets the only inline-four M10 post-facelift model available was the 1.8-litre 518 which carried on as the base model until the end of production.

For the 525 and 528 models, the dual Zenith carburettors were replaced with a single Solex 4A1 DVG four-barrel, which increased power to in the 528.

File:Bmw e12 v sst.jpg| Pre-facelift front until 1976 (four-cylinder)

File:BMW 528 (E12) – Frontansicht, 22. August 2013, Münster.jpg| Pre-facelift front (six-cylinder)

File:BMW 528 (E12) – Heckansicht, 22. August 2013, Münster.jpg| Pre-facelift rear

File:BMW-E12-Front.jpg| Post-facelift front

File:BMW-E12-Heck.jpg| Post-facelift rear

BMW-E12-Interieur.jpg|Interior Post-facelift 1976

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1978

The 528i model, using Bosch L-Jetronic fuel injection, begins production in July as a replacement for the carburetted 528 which was discontinued in September 1977.

1979

535i Motorsport available as special order only The latter caused several engine problems including burned exhaust valves and overheating, often resulting in warped or cracked cylinder heads. A separate defect in the 530i cylinder head design prompted a lawsuit against BMW. As a result, in 1980 BMW offered replacement cylinder heads for owners whose cylinder heads had cracked, even if the warranty on the car had expired.

For the 1979 model year, the 528i replaced the 530i for the American market. To reduce emissions, the thermal reactor and air pump system were replaced with a 3-way catalytic converter and the car's Bosch L-jetronic fuel injection system was now fitted with an exhaust gas oxygen sensor. Power was reduced by , and the presence of the catalytic converter meant that unleaded gasoline (petrol) was required. In spite of widespread sanctions, locally built E12s also saw some export, the 520 being sent to Argentina and the 518 De Luxe to Belgium, Iran, and Italy.

Critical reception

While being commended for its acceleration and build-quality, Modern Motor criticised the 1978 528i for unpredictable handling and excessive body roll. Steering corrections during cornering meant the car's body "lurches back annoyingly and messily", in part due to the soft springing and hard damping combination. In comparison to the Jaguar XJ6 and Peugeot 604, the car was viewed as narrow and cramped in the rear and prone to wind noise.

Production

Production of the E12 occurred from June 1972 to 1981, with a total of 699,094 cars produced. Initially, the cars were produced in Munich, West Germany. Following the opening of the new BMW Group Plant Dingolfing in September 1973, production was phased over to the Dingolfing plant.

Complete knock-down assembly of German-produced kits took place in Rosslyn, South Africa; Jakarta, Indonesia (by Gaya Motor); and Thailand.