Concluding the story of the BMW E12-generation 5 Series.
The new 5 Series received a generally positive if not euphoric reception from the automotive press. With its 2-litre four-cylinder engine, it was not powerful enough, even in fuel-injected form, to exploit fully the capabilities of its chassis, and the engine itself was somewhat lacking in refinement when pushed hard.
BMW answered these criticisms in 1973 with the introduction of the 525. This was fitted with a straight-six SOHC engine with a capacity of 2,494cc which produced maximum power of 143bhp (107kW). Stiffened front springs and a thicker anti-roll bar were fitted to counter the extra weight of the engine. The 525 was fitted with disc brakes on all four wheels. Power steering and a limited-slip differential were now on the options list. Badging apart, the only external identifier for the new model was a subtly different bonnet: the 525 had a slightly raised centre section instead of the slightly indented section on the 520.
Car Magazine published its first impressions of the 525 in October 1973 and these were very positive: “the sheer performance was predictable, but the smoothness, flexibility and sweetness of [the] package was more of a surprise. It will potter along at very low speeds in top, rarely needs anything lower than third once on the move and will storm to over 120mph with beguiling ease.” The reviewer went on to say that “This is not a busy BMW like the 520 and 520i. It performs with great ease and can turn in some startling acceleration figures when required.”
The heavier, more powerful engine caused some issues with wheelspin, however, affecting both performance and handling: “it was even possible to get a pretty substantial cheep from the rear wheels when going from second to third gears.” When cornering hard, “the inside wheel would lift and chew its rubber off with very little provocation.” The reviewer suggested that the limited-slip differential, not fitted to the test car, would likely mitigate this issue. The reviewer concluded that the 525 was “a remarkably good car that is going to suit a lot of people even as it stands, but a lot more will like it if the inner wheel lifting problem can be overcome gracefully.”
When the magazine next tested the 525, it pitched it against the Jaguar XJ6 and NSU Ro80 in a Giant Test, published in the August 1974 issue. There was no mention of wheelspin with the 525. In fact, it was rated “the best handler of the three and we believe it has the best roadholding. There mightn’t be much between it and the Jaguar in the dry, but the BMW has a clear edge in the wet.” There was no indication as to whether or not the test car was fitted with a limited-slip differential, but one might assume that this was the case.
BMW expanded the 5-Series range in both directions in 1974, adding an entry-level 518, a 528 and range-topping 533i. The 518 was powered by a 1,773cc version of BMW’s M10 inline-four engine fitted to the 520. It produced maximum power of 89bhp (66kW). The 528 was powered by a 2,788cc version of the M30 inline-six, producing 162bhp (121kW). The range-topping 533i was powered by a 3,210cc(1) fuel-injected version of the same engine, which produced maximum power of 197bhp (147kW).
There was a further engine addition to the line-up in 1975, albeit for export markets only. A 2,986cc version of the M30 inline-six was added. This was exported to South Africa in carburettor form producing 178bhp (132kW) where it was badged 530, and to the United States(2) in fuel-injected form producing 197bhp (147kW) where it was badged 530i. On the 520i, the Kugelfischer fuel-injection was replaced by the Bosch K-Jetronic system. This actually caused a slight drop in maximum power output to 123bhp (92kW).
The 5 Series was given a subtle facelift in 1976, overseen by Claus Luthe. The most obvious change was that the leading edge of the bonnet now had a raised centre section to accommodate the double-kidney grille(6), which no longer dipped behind the front bumper. Both four and six-cylinder versions now shared the same bonnet. At the rear, there were enlarged light clusters and the fuel filler was moved from the rear panel to the right-hand rear wing. New, larger door mirrors were now mounted on a sail panel in the corner of the window rather than on the door skin.
In 1977, the 520 received a 1,991cc M30 inline-six in place of the M10 four-cylinder unit and was renamed 520/6. The new engine produced maximum power of 121bhp (90kW). A year later, the 528 was replaced by the 528i, using Bosch L-Jetronic fuel-injection and producing maximum power of 181bhp (135kW).
While there was never an M5 badged high-performance version of the E12-generation 5 Series, the 1980 M535i, built by BMW’s Motorsport division, was one in all but name. The new engine, still a SOHC inline-six, was fitted with Bosch L-Jetronic fuel-injection and tuned to produce maximum power of 215bhp (160kW) and torque of 220 lb ft (310Nm).
The engine was mated to a five-speed Getrag manual gearbox with first gear offset to the left and the other four in an H-pattern. BMW claimed a 0 to 60mph (97km/h) time of 7.4 seconds and a top speed of 140mph (226km/h). External modifications were very discreet, just a deeper front air-dam and a rubber spoiler on the boot lid. Inside, it was equipped with individual Recaro bucket seats front and rear, making it a strict four-seater.
Car Magazine’s Georg Kacher drove the new model and reported his findings in the January 1980 issue. Kacher was hugely impressed by the M535i, describing it as “just plain fast, and it covers long distances quickly and effortlessly thanks to the beautiful blend of steering, brakes and suspension.” He thought that “the steering is perhaps the biggest advance over the lesser models” being “extremely precise and quick.” The handling was “reassuringly taut instead of slightly nervous” and the brakes were “beyond criticism; four ventilated discs get exactly as much servo assistance as they need.”
On fast secondary roads The M535i was “at its best; fast, safe and – believe it or not – sufficiently comfortable” and it “just goes where you point it.” It was safe because “long before the car actually lets go, it will warn the driver; first the steering gets slightly lighter as more power is applied to the rear wheels, then you have to reduce the lock as the M535i swings from neutral to a progressive oversteer [so] there is enough time for easy and smooth correction at the wheel.”
There were some minor niggles concerning wind noise and the efficiency of the interior heating and ventilation system, but the car was a real tour de force. It might have taken eight years(3) to arrive, but the M535i really cemented BMW’s reputation as a builder of beautifully handling sport saloons. The only disappointment for buyers in the British Isles was that it was not available in RHD.
Over a nine-year production run, just short of 700,000 E12-generation 5 Series were built in Munich and Dingolfing(4) and another 23,000 in South Africa, where the model remained in production until 1984. It was a hard act to follow and when BMW replaced it in 1981, the E28-generation successor was, at first glance a very cautious update which looked more like a heavy facelift than the wholly new model it was.
In any event, the new model built on the E12’s success and we have now reached the seventh iteration of the 5 Series, the 2016 G30-generation model. Of course, the proliferation of SUVs, crossovers and, more recently, EVs in BMWs model range means that the 5 Series is no longer nearly as important to the company’s image and success.
(1) It should logically have been badged 532i but BMW preferred to round up in this case.
(2) BMW had a number of early reliability issues with US market E12 cars, mainly due to the modifications required to satisfy federal regulations. The cars were vulnerable to overheating and suffered from warped or cracked cylinder heads, causing expensive warranty (and post-warranty) claims. Which BMW honoured in full.
(3) BMW Motorsport (now renamed BMW M) offered special upgrade packages for E12 models from 1974 on, but the M535i was its first stand-alone model.
(4) A BMW plant in Lower Bavaria opened in September 1973 on the site of the former Glas auto works.