BMW 2012 528i : Four goes into five

The 2012 528i is a huge risk for BMW. Yes, I know it's just a 5 Series, in fact the most basic - if any mid-sized, luxury saloon by BMW can be called "basic" - of all 5 Series. Indeed, a 5 Series has proudly worn the "28" badging in various guises since 1975. So, what can possibly be the big deal about the 2012 version?

The issue is that we embrace our luxury cars writ large. Bigger is better, bolder is best and we generally like as many pistons crammed under our bonnets as possible. Eight are better than six, 12 better still, and wouldn't you get laughed out of the showroom if you tried to foist four picayune cylinders on the monied set. They might not recognise a piston from a hair roller, but they do know that four of them is simply not enough; Road & Track told 'em so.

Yet BMW - as all automakers the world over - is struggling to meet ever more stringent fuel efficiency standards. Whether it be the EU's 120 grams/per mile CO2 mandate or president Obama's 56.2mpg dictum, the trick is to try to go further on a gallon of petrol while still managing to spoil its better-off clients in the manner they've become accustomed to.

That's why BMW, like Ford, Mercedes and Audi, has embraced turbocharging recently. I dare say that Munich would deem their EfficientDynamics interpretation of the exhaust-driven-supercharger (for that is what a turbocharger is) more sophisticated and efficient, but the premise is the same: replace big V8s with smaller turbocharged versions, small V8s with blown sixes and sixes with turbo'ed fours. Smaller displacement and fewer pistons promise superior fuel economy while the turbochargers guarantee there's sufficient power when called upon.

The programme works a treat at its upper echelons. Though purists will no doubt lament the passing of M5's high-revving 5.0L V10, the rest of us find solace in the incredible 560hp that the latest M5's twice-turbocharged 4.4L boasts. Same goes for the garden variety 650i I tested recently; 400hp of immediate throttle response hardly seems like a huge sacrifice to fuel economy. And the 335 and 135 M Coupé's force-fed 3.0L inline six is simply one of the sweetest engines ever, making me completely forget the V8 that powers the current M3.

But now comes this latest version of the company's iconic 528 and it's trying to foist a four-cylinder on a much more discerning clientele. Not only do 5 Series customers have loftier expectations but also greater experience in luxury cars. How will the clientele of an estimated Dh240,000 (no prices are available for the 528i here yet) luxury saloon react to having four measly pistons underfoot when they've long been accustomed to six or eight?

If BMW had simply dumped the X1's 2.0L, as is, into the 5 Series, I suspect that things might not have gone swimmingly. Adequate for that intended audience, as installed in the baby SAV, the 2.0L was hardly soniferous or wonderfully smooth. One never missed the six's power, but the four's comportment lacked a certain sophistication.

Not so the 528's application. With different engine mounting, superior noise attenuation and some judicious exhaust pipe tuning, the small four cylinder is, with one small exception, right at home in the 528. First and foremost, it never, ever, feels underpowered. Though the 2.0L's numbers are impressive - 240hp and 350Nm of torque - they don't convey how truly powerful the engine feels at low rpm. Indeed, though many of us associate turbos with high-rpm racing, the true magic of turbocharging is its ability to let small engines produce the low-end torque of big engines. Mated to the smooth-shifting eight-speed transmission and its gear for every purpose and power, this is one slick powertrain. BMW claims 6.6 seconds are needed for the 528 to accelerate to 100kph, impressive numbers at the very least. But the real trick is how effortlessly the four pistons make the entire process.

Its performance didn't surprise me quite as much as its comportment. Loyal readers will know that I am a huge fan of BMW's inline sixes, if not for their pure power, then the "ripping silk" music they make when screaming for the redline. No four can compare.

And, indeed, the 2.0L can't. But, and this is perhaps the 528's biggest surprise to me, it's not so bad. At low speeds, the 2.0L is a little tramp-steamerish, its exhaust note a tad droning. But, it's well subdued and since it's unaccompanied by any vibration, it's not very noticeable. And unlike other inline fours, save perhaps Audi's exemplary 2.0T, when you matt the throttle and the revs start flying, the little four sounds, dare I say it, almost sporty. No, it's not five-octave Mariah Carey but neither is it fingernail-scratching-chalkboard Avril Lavigne. Four will never replace six in this regard but, in circumstances where other four-cylinders might embarrass, BMW's sounds the part.

As for fuel economy, I have to say turbocharging is only partially successful in improving real world fuel economy. Certainly, any gains in efficiency require that you not dip into the 2.0L's horsepower well; otherwise, it's as profligate as any other 240hp engine, four pistons or no. I suspect that most people won't have much problem approximating the 528's 5.9L/100km motorway rating, but playing with the N20's responsive throttle will make the city 8.8L rating less attainable. BMW has added an "EcoPower" mode that sees the 528 shifting early, but then, thanks to the aforementioned prodigious low-end torque, it hardly affects driveability, even when shifting at 2,500rpm. That said, I averaged only about 11L/100km in my time in the 528, no doubt the result of my frequent toying with the turbochargers.

I came away from a week in the 528 even more convinced of BMW's switch to turbocharging. Yes, I will miss the inline six (and, indeed, if they ever get rid of it completely, I will be the first to shout from the rooftops). But if the 528's little four is the invention that all these new fuel efficiency regulations necessitate, then the future is not so bleak after all. The new four-cylinder not only matches the old six's performance; it exceeds it.

The 528i should appear in UAE showrooms by early next year.