Four goes into Five.
If you wanted to find a four-cylinder engine under the hood of a Canadian BMW 5 Series, you would have to go all the way back to the E12 generation (1972-‘81). It was a widespread era of chocked performance and anemic outputs and most cars still had these funny things called ‘carburetors’ delivering fuel to engines of the time. Since those dark ages much has changed and the automotive collective has come to expect inline-sixes under the hoods of most BMW products, especially the midsize 5 Series. In an act of history repeating itself, BMW has resorted to installing the inline-four in that very model range. This could be a questionable call because back then, four cylinders weren’t known as benchmarks of refinement, and although modern engineering has vastly improved them, they’re still not great.
It’s not that automakers are lazy and take a halfhearted approach to engine noise, vibration and harshness (NVH). It’s that the inherent layout of a four-banger causes coarse secondary vibrations and other associated nastiness. Powertrain engineers have to employ all manner of solutions to quell this uncouthness–this adds weight, cost and complexity. Despite those tricks they don’t have the natural balance of say, an inline-six, an engine architecture BMW has become quite good at producing throughout its history.
So when the boys in Munich announced they were installing an inline four again in some of their smaller products (debuted in the X1/Z4, will follow shortly in the 3 Series.) Some folks weren’t crazy about the shift to smaller engines but acknowledged and accepted their reemergence as a sign of the times. But put that engine in a 5 Series? This we had to see for ourselves, so we bring you this insight into BMW embracing this architecture. Like many “new” ideas, this one requires delving into the past.
It’s an impressive history that includes some formidable engines- my favorite would have to be the 1.5-litre turbo that powered Nelson Piquet to the Formula 1 world championship in 1983. The little scamp was nothing to laugh at–it maxed out the dynamometers at BMW’s factory, and it provided readings up to 1400 horsepower. Oh, and who can forget the first generation M3 with its rip snorting four-banger? At all points along the company’s timeline, BMW has been constantly raising the bar on engine development. All that experience coupled to modern staples like direct injection and turbocharging have allowed BMW to build what I believe to be the most well executed four-cylinder engine to date.
Except for a louder than expected tick-tick-tick at idle from the high pressure fuel injectors, the engine (known internally at BMW as N20) will go about its business largely unnoticed. Its polished demeanor allows zero undue NVH to enter the passenger compartment, neither through the steering wheel, pedals or trim bits. Its power curve is better described as a plateau, not the on/off nature you might expect of a small displacement forced induction mill, and its thrust tapers off only in the far upper reaches of the tach. Incidentally, it’s only those last thousand revs or so that threaten to lift the velvet curtain BMW has shrouded its four-banger in. I suspect that it’s not out of the question for this engine will make it into the engine bay of the larger 7 Series in some markets.
Other benefits of the 528i other than refinement? With less mass at the front of the car, it becomes sharper in its willingness to change direction. Improved fuel economy is an obvious benefit as well. At this time BMW hasn’t announced official fuel consumption numbers, but I achieved an observed 11.2 litres per 100 kilometers in combined driving- not bad at all.
When we last drove the 5 Series, it was powered by the turbo inline-six. Other that what was under the hood and drivetrain configuration (our 528i had xDrive all-wheel drive) everything was exactly the same this time around. I’d be hard pressed to find a better car to digest huge amounts of kilometers in serene comfort. Our tester was even more pleasing to the eye with its meticulous stitching across the dash and console, and the baseball glove leather/dark birch wood combination were a welcome indulgence.
Our tester had a whole score of electronic driver aids including lane departure warning and blind spot monitoring. You know what? I didn’t use ‘em. Call me a curmudgeon, but I’m still not sure about all those technologies that keep tabs on things you should be paying attention to as a driver in the first place. Not only that, but I felt like they acted almost like electronic buffer over the organic feel of the 5 Series.
That organic feel has suffered somewhat since the days of the E39, still widely regarded as the best 5 Series ever. Part of that is owed to BMW’s shift to electronic power steering. It still lacks the hard wired sense of control the company’s hydraulic systems impart, but I get the sense BMW engineers have been working hard at this, and the payoff is much better feel than I remember.
If what you’ve just read doesn’t convince you that the world hasn’t gone mad because of the existence of a four-cylinder powered 5 Series, I don’t blame you. I wasn’t convinced that engine configuration would ever feel right under the hood of the 5. That was before I spent a week with it. The future of the four-banger suddenly looks brighter.
2012 BMW 528i- Specifications
Price as tested: $70,250
Body Type: 4-door, 5-passenger sedan
Powertrain Layout: Front engine/all-wheel drive
Engine: 2.0-litre inline-4 turbo, DOHC, 16 valves
Horsepower: 240 @ 5,000-6,500 rpm
Torque (lb-ft): 258 @ 1,250-4,800 rpm
Transmission: 8-speed automatic
Curb weight: 1,815 kg (4,001 lbs)
Observed combined fuel consumption: 11.2L/100 km (21 US mpg)