You can often tell how successful a model has been when it gets a refresh. If the changes are modest (say, a styling tweak and a modest slug of extra equipment), then the car is probably selling well.
That's the case with the BMW 5 Series sedan. Now in its sixth generation, the latest 5 Series has been the fastest selling yet, with over a million sold worldwide in three years.
Then again, if you see substantial upgrades as part of a refresh, then the manufacturer is likely tackling a few criticisms to give a struggling model a boost. Case in point, the 5 Series GT. Its awkward looks and odd position within the lineup have made it a much slower seller, so it gets a rear-end restyle along with repackaged accommodations.
Likely to be bigger news than the GT's makeover is that the 5 Series sedan will be available with a diesel engine. Dubbed the 535d, it puts out a stout 254 horsepower and an even stouter 414 pound-feet of torque, enough to deliver a 0-62-mph sprint in an admirably brief 5.3 seconds.
And though BMW has yet to publish mileage figures for the car, you can expect the numbers to come out looking far more impressive than the 535i.
The other major engine development is the arrival of a new version of the 4.4-liter V8 in the 550i. It's now equipped with Valvetronic breathing gear and a twin-scroll turbo, so power climbs from 401 hp to 444 hp to yield an impressive 0-62-mph time of 4.6 seconds. An all-wheel-drive 535d xDrive will be available as well.
The rest of the engines in the range remain largely unchanged.
We enjoyed the mounds of torque delivered by the oil-burning straight-6, finding it far more flexible than expected. To experience the full storm of its 414 lb-ft of torque it's best to switch the eight-speed auto into Manual mode, select 2nd, slow to a 1,000-rpm crawl and crush the accelerator like an unwelcome cockroach.
There's a brief gathering of speed until 1,500 rpm arrives, at which point the BMW hunkers down under the sheer force of torque muscling its way to the rear wheels, the ensuing surge as exciting as anything a gasoline engine can muster 4,000 rpm later.
Still more surprising, if you're used to the historically compact rev ranges of older diesels, is that the thrust keeps on coming through to 5,000 rpm, before petering out over the final few hundred revs. This diesel is memorably quick and better yet, makes a smooth, low, muffled rumble that's just as entertaining as the slightly synthetic-sounding crescendo of the 535i.
The 5's chassis has also seen a light rethink in the form of retuned dampers for improved comfort, quietness and reduced roll, besides some fresh mapping of the electric power steering to sharpen its precision.
These dynamic upgrades are subtly apparent on the admittedly shelf-smooth Bavarian roads we sampled it on. The ride is smoother, the cabin is a little quieter and body sway, never a big issue in a 5 Series, is tightly controlled. The natural balance that comes from this car's rear-drive layout makes it impressively wieldy through curves without feeling nervous.
That said, we still consider the optional electronic dampers to be a 5 Series essential for a compliant ride on turbulent terrain, and if you have them it's useful to firm the BMW's body control for seriously hard charges.
The revised steering feels a little more accurate, too, even if you need the Sport setting for the most consistent, confidence-building rim resistance. This you select via BMW's increasingly familiar "driving experience" rocker switch on the center console. It toggles among the fuel-saving, throttle-dulling, Eco Pro mode and the Comfort+, Comfort, Sport and Sport+ modes, the last of these partly disabling the stability control.
Each setting adjusts the steering feel, throttle sensitivity, transmission and, if they're fitted, the firmness of the electronic dampers. It works to good effect, though you quite often find yourself wanting a combination of softer suspension, say, and a sharper throttle. Configuring these settings individually, Audi-style, would be better.
Modest Styling Changes
And at first glance, you might think that the entire car is unchanged. Spotting a 2014 model-year 5 Series sedan isn't easy at first, but from the front it's identifiable by remodeled lights and a resculpted nose section that mirrors the hooded-eye look of the 3 Series.
The rear bumper is new, too, as are the taillights. The side indicators now live in the mirror housings rather than on the fenders, and some versions flaunt modest dashes of extra brightwork.
The biggest change inside is a switch to flat-screen, reconfigurable gauges. They're red-lit when you select Sport, for instance, while the speedo readout goes digital — and there are some detail decor enhancements. The infotainment system's capabilities can be optionally deepened with an iDrive controller that doubles as a mouse, besides allowing the dictation of texts and e-mails.
Later this year there'll be an optional self-parking system requiring no control inputs of any kind, and a traffic jam assistant allowing the 5 Series to steer, accelerate and brake with no intervention from the driver at speeds of up to 19 mph in traffic.
Is It Enough?
There's no question, then, that the 5 Series diesel we drove is a very accomplished car. And it was more sporting than you might expect, with the 3.0-liter diesel sounding keener and producing more instant go than the gasoline-powered 535i.
It's fast, quiet, rides well and delivers the effortless journeying that cars like this are supposed to be about. It also has a roomy, beautifully crafted cabin, packed with electronic convenience items if your wallet is fat enough to afford them.
Of course, the diesel model is just one small piece of the larger 5 Series pie. The rest of the lineup will likely attract the bulk of the sales in the U.S., and the minor nips and tucks made to all the models will surely keep them competitive. The only downside to this latest refresh is its modesty. Anyone hoping for some big changes to the 5 Series this time around will have to wait another couple of years, and BMW doesn't seem too worried about it.
Edmunds attended a manufacturer-sponsored event, to which selected members of the press were invited, to facilitate this report.