BMW has a long and storied history of developing class-leading engines, to the point that even its headquarters in Munich, Germany is meant to represent the four cylinders of a car’s engine. But while it has built some impressive four-cylinder motors in the past, this is not the configuration that it is most widely known for today.
- Base Trim Engine
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3L I6 ICE
- Base Trim Transmission
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6-speed manual
- Base Trim Drivetrain
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Rear-Wheel Drive
- Base Trim Horsepower
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473 HP @6250 RPM
- Base Trim Torque
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406 lb.-ft. @ 2650 RPM
- Base Trim Fuel Economy (city/highway/combined)
-
16/23/19 MPG
Where research meets the right deal
The engine layout that has separated BMW from the rest is, of course, its range of inline-six masterpieces. But BMW’s first inline-six wasn’t fitted to a car at all. We look at the history of BMW’s inline-six engines and the fascinating journey the marque has taken since its inception in 1916.
All information is from reputable sources.
BMW’s Beginnings
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BMW IIIa Aircraft Engine |
|
|
Engine |
19.1-liter inline-six |
|
Power |
180 hp+ (226 hp at ground level) |
|
Torque |
n/a |
|
Introduced |
1917 |
BMW’s first inline-six engine was called the BMW IIIa, a 19.1-liter water-cooled six-cylinder motor developed for use in aircraft. Introduced in 1917, it preceded its automotive equivalent by 16 years. That’s because, like so many legacy manufacturers, the history of BMW is not as straightforward as you might think.
While BMW (Bayerische Motoren Werke AG) was founded on 7 March 1916, its origins date back to 1910. We cover BMW’s history in great detail here, as well as why that BMW logo may not represent what you may think it does, but for this article, and to keep you interested, let’s cover the high points of BMW’s inline-six journey in a short table summary below:
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Date |
Event |
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1916 |
Gustav Otto Flugmaschinenfabrik merges with Bayerische Flugzeug-Werke AG (BFW) on 7 March. This date was later also chosen as the founding of Bayerische Motoren Werke AG (BMW) |
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1917 |
IIIa inline-six aircraft engine introduced |
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1933 |
M78 inline-six developed for use in the 303 road car |
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1968 |
M30 inline-six introduced. Notable applications include 3.0 CSL and 635 CSi |
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1978 |
M88 inline-six debuts in M1 supercar and is also used in the first-ever M5 |
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1989 |
M50 inline six launched in E36 3 Series |
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2000 |
S54 inline-six M-specification engine debuts in E46 M3 |
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2006 |
N54 twin-turbo inline-six motor debuts in E90 generation 3 Series |
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2015 |
B58 turbocharged inline-six engine offered in the F30 BMW 340i |
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2019 |
S58 twin-turbo M-Spec engine first introduced in the F97 X3 M and F98 X4 M |
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Big grilles, crazy engines, and a dark past.
Aim for the sky
It’s been 108 years since the BMW IIIa engine debuted, and while the 180-hp it produced may seem paltry by modern standards, remember that airplanes had only been invented 14 years earlier, and the IIIa was actually one of the most potent aircraft engines in service at the time.
Foreshadowing the automotive rivalry with Mercedes that was still decades away, the IIIa replaced a less powerful Mercedes-Benz engine when it was put into service in the German Fokker D.VII airplane. Not only was it more powerful, it also had an altitude-adjusting carburetor, allowing it to perform far better at high altitudes than rival designs. The III in its name marked it out as being in the top power output tier of aircraft engines at the time.
The rocky road to the straight-six
BMW’s road-bound efforts took a bit longer to get rolling, partly due to the fallout from the war, which impacted its production capabilities and infrastructure. The BMW R32 motorcycle was released in 1923, featuring the iconic boxer two-cylinder engine. It wasn’t until 2010 that the inline-six made its way into the motorcycle range, in the form of the K 1600 GT grand tourer.
Automotive Intro
The car division got off to a slower start in more ways than one. BMW’s first road car arrived in 1929 and was a rebadged British Austin Seven, also known as the Dixi 3/15. Its tiny 0.75-liter four-cylinder engine made just 15 hp. Four years later, the BMW 303 was launched, featuring the marque’s first inline-six engine designed for road cars. It was produced from 1933 to 1950, and featured an overhead-valve design with capacities between 1.2 and 1.9 liters. Power outputs ranged from 30–54-hp.
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BMW M78 Automotive Engine |
|
|
Engine |
1.2-1.9-liter inline-six |
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Power |
30–54 hp |
|
Torque |
50–77 lb-ft |
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Produced |
1933-1950 |
The turnaround
After another period of upheaval following the Second World War, BMW slowly rebuilt its business, and the introduction of the M30 inline-six range of engines in 1968 marked a major turnaround in its fortunes. This engine would go on to power some of the most iconic BMW models of the 1970s and 1980s, remaining in production for 24 years. Subsequent inline-six engines like the M20, M50, and B58 have all gone on to be class-leading motors, developing excellent power for their size, and being renowned for their smoothness.
The Inline-Six Engine
BMW has experimented with just about every engine configuration over the years, including flat-twins, inline-threes, inline-fours, V8s, V10s, V12s, and even a V16. What it has never built is a V6, preferring to stick to the inline-six throughout. There are several reasons for this.
An inline-six engine has perfect primary and secondary balance, making it extremely smooth. It is a simpler design than a V6, requiring fewer components and no balancer shafts. The only drawback is its length, which makes it very difficult to mount transversely (although Volvo did it once), but this is not an issue in BMWs, as they are mounted longitudinally, which works perfectly with the rear-wheel drive design.
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The B58 is a surprisingly adaptable engine and can provide varying levels of power to suit many different cars and powertrain combinations.
Aside from a V12 (which is two inline-sixes mounted together), the inline-six is the smoothest engine configuration around. It also allows for linear power delivery and provides strong low-end torque. Some of the world’s most powerful six-cylinder engines have come from BMW’s M Division, with engines like the M88, S54, and S58.
It is worth mentioning that there have also been some pretty amazing BMW engines of all cylinder counts, including the S14 inline-four as found in the original M3, the S65 V8 from the E90 M3, and the V10 S85 from the E60 M5. BMW also developed the S70/2 V12 motor that was used in the McLaren F1 supercar.
The Future Of BMW’s Inline-Six
The past decade has seen a great deal of change take place in the automotive industry. Electric vehicles and hybrids have advanced hugely, and even gas-powered engines are more efficient and powerful than ever before. The BMW inline-six engine has also evolved, getting updated with fuel injection and double overhead cams, variable valve timing, direct injection, and turbocharging over the years.
BMW’s current S58 3.0-liter twin-turbo inline-six engine is still the motive force behind its most desirable M models, and the B58 turbocharged 3.0-liter inline-six powers everything from compact coupes to the largest SUV in its portfolio.
To enhance longevity and efficiency, mild hybrid technology has been added to most models using the B58 motor, and plug-in hybrid versions of this engine are also offered in the X5 xDrive 50e and XM 50e as well. The S58 engine is also rumored to be getting a complete makeover in the coming years. According to Dr Mike Reichelt – the man behind the Neue Klasse models – we can expect a new type of six-cylinder engine in the next generation M cars.
Currently, the limited edition 2023 552-hp 3.0 CSL holds the title of most powerful road-going BMW inline-six ever. And to demonstrate just how far we have come, if that original 19.1-liter IIIa aircraft engine had been developed with this level of technology, it would have made an insane 3,514 hp instead of 180-hp.
Sources: BMW
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