Ostensibly, the ongoing switch in the luxury segment from large, naturally aspirated engines to smaller turbocharged ones is all about increasing fuel economy. The concept is simple: reduce the displacement of the engine so that fuel consumption during everyday driving is minimised and then add a turbocharger so that, on demand, said smaller engine can produce more power. Any performance enhancement, if one listens to the corporate publicity wonks, is supposed to be secondary.
In reality, the increase in performance is the most obvious difference. Take Mercedes's latest upgrade to the S550 as an example. Last year's version was powered by a 5.5L normally aspirated V8; the 2012 S550, meanwhile, sees a twice-turbocharged 4.6L V8 under the bonnet (Mercedes maintains the previous "550" designation because a] it prevents confusion and b] it sees the blown 4.6 as "equivalent" to 5.5L). One could, one supposes, try to pawn off the new car's 47 extra horsepower (429 in all) as a largely inconsequential advantage in a monster luxury saloon that weighs 2,075kg, but trying to relegate the new turbocharged engine's extra 169Nm of torque (700Nm in all), taking it to 100kph in less than five seconds as a mere by-product, stretches the credibility of even the most silver-tongued public relations hack.
The real benefit to all this turbocharged muscle, however, is not in how quick the big Merc accelerates but how all that performance is dispensed. Again, the extra 47hp matters not; the big news is that extra 169Nm of torque and when and how it's produced. Being twice turbo'ed - two small turbochargers are more efficient at low speeds than one large one - means there is simply bucket loads of torque at these same low speeds.
In fact, low-rpm torque is so prodigious that the engine usually shifts around 2,000rpm. Three thousand rpm is seldom needed and, except for one quick burst (only for verification of performance, of course), I never took the car over 4,000rpm. By that time I was accelerating so hard that I was starting to scare Corvette drivers. And, even then, the powerful, low-revving engine seemed like it was loafing as if, despite the telephone poles blinding by, grandma was at the wheel driving to the shops for groceries.
And so, despite those boasts of both five-second-flat acceleration times and frugal fuel consumption, it is this effortless ability to stay ahead of traffic that is the S550's most entreating character. Mercedes-Benz has always calibrated its automatic transmissions for reluctant downshifts, the theory being that kicking down a gear was an abrupt intrusion into what was supposed to be a seamlessly smooth ride. The problem was, for those of us with, er, tighter schedules, the lack of acceleration would encourage us to dig even deeper into the throttle until, when the trannie finally did downshift, the resultant flurry of revs and hard gear change really was abrupt.
The new powertrain, however, is so tremendously powerful that it hardly ever needs to downshift. Indeed, I kept the engine in its "economy" mode (surely an oxymoron in a 429hp automobile), which deliberately restricts downshifts, and still the S550 powered relentlessly ahead like Kirstie Alley heading for the buffet table. Indeed, though the S550 gets the latest iteration of Mercedes' seven-speed automatic transmission, it could probably restrict the big V8 to two forward gears and nobody would notice. The bottom line is that not only is the new S550 more powerful than its predecessor, it also feels much more refined.
Refinement by way of technological advancement certainly fits in with the rest of the S550. Not only is the 550's cabin imbued with all the niceties that a luxury car should bring - leather, wood, chrome, etc - but there's a virtual smorgasbord of computerised gadgets to relax, coddle and protect you from the elements.
It should almost go without saying that seats are both heated and cooled. Same goes for supportive padding and leather worthy of a Bauhaus sofa. The optional Drive-Dynamic seats, though, are cool, not only massaging you with the proverbial 1,000 tiny fingers while you lounge, oops, drive, but also automatically provide additional side bolstering (via rapidly inflating air bladders) when cornering.
The only issue is that the seats, like anything even remotely safety-orientated in an automobile these days, can be overly aggressive. Even just turning into your driveway has the seat reacting as if you just tossed an SLS into Daytona's banked turn three in top gear.
Thankfully they are adjustable, although, even in their minimum position, I found them intrusive at low speeds.
Also available are such safety nannies as Distronic Plus - an active cruise-control system that maintains a minimum distance to the car ahead, Active Blind Spot Assist, which uses radar to ensure you don't switch lanes into that lowly Passat beside you, and Active Lane Keeping Assist, which vibrates the steering wheel like a rumble strip every time you switch lanes without using the indicators. The 2012 Mercedes-Benz S550; the car as overbearing as mother-in-law.
Very interesting, however, is the Splitview dual-content screen for the COMAND system's on-board computer. By dividing the screen in two, Splitview allows the driver to view navigational directions while the passenger watches a film. With entertainment systems now available for front and rear seats, both kids and spouse can now be placated, making Splitview possibly the greatest enhancement in automotive luxury in decades.
Quibbles are few. Although economy was the reason for the switch to turbocharging, your actual, real-world consumption is now even more dependent on your right foot. I averaged about 12.0L/100km, but that was in economy mode. The poor hack before me averaged 18.0L/100km, which just goes to show you how quickly that supposed fuel economy advantage of turbocharged engines disappears if you exercise your right foot.
But the true upshot of the 2012 550 is that new turbocharged engine transforms the big saloon's character.
It's not even how truly fast it is but how slow it can make going fast feel. I have always thought of Mercedes as the lesser potentate's Rolls-Royce - the way station on the path to ostentatious wealth - and while it should always boast sufficient pace, the emphasis should always be on the grace. At once speedier and more elegant in its comportment, the S550 is now much more the prestige automobile it has always purported to be.
And that's why it's too bad for drivers in the GCC; the S550 isn't even offered here.
Price Not available in the GCC
Engine 4.6L turbocharged V8
Gearbox Seven-speed automatic
Power 429hp @ 5,250 rpm
Torque 700Nm @ 1,800 to 3,500rpm
Fuel economy, combined 9.8L/100km
