Route guidance works well; we especially like how it shows which lane you should be in before a freeway intersection. But it doesn't offer text to speech. And, as we pointed out above, although it shows traffic incidents, it won't warn ahead of time about traffic jams on your route.
We also mentioned the poor iPod integration. The S550 comes with a few other means of playing music, the most esoteric being a PC Card slot in the center dash, designed for MP3 tracks loaded onto flash memory. The six-disc in-dash changer reads both MP3 CDs and DVDs. The stereo receives both Sirius satellite and HD radio.
Harmon Kardon provides the Logic 7 audio system, making music from these sources sound very good. With 14 speakers and 600 watts of amplification, its sound is very well-balanced, producing distinct highs and reasonable bass. Mid-ranges come out strong, making vocals easy to hear. Similar to other aspects of this car, the audio quality doesn't make itself obvious, merely coming through cleanly, without drama.
Of the driver aids, the new blind-spot warning system is the most useful, providing ample warning about cars that might have sneaked into your blind spot. Adaptive cruise control is also quite nice, making long freeway cruises in moderate traffic effortless, at least as far as your feet are concerned.
Night vision is a truly remarkable feature, but of less utility. It can be activated only in the dark, and replaces the speedometer display with an enhanced black-and-white view out the front. Vehicle speed is displayed on a horizontal bar below the forward view. Night vision comes in handy when driving through dark forests or country side, as a glance down at the display lets you see much further ahead on the road than you can unaided.
Under the hood
With the launch of the S550 in 2005 came Mercedes-Benz's new 5.5-liter V-8, which has since seen service in many other of the company's models. The engine's size goes against the grain of today's more fuel efficient mindset, but it gets mitigated somewhat by the seven-speed-automatic transmission. Those higher gears go some ways toward increasing the miles per gallon at freeway speeds.
The EPA rates the S550 at a dismal 14 mpg city and 22 mpg highway, opening it up for a gas guzzler tax. During our testing, with driving biased towards the freeway, we saw an average of 19.8 mpg.
We pointed out the acceleration above, made possible by the engine's 382 horsepower and 391 pound-feet of torque. Even with the size of the S550, this engine never feels strained. The transmission has a stalk for putting it in drive and reverse, and there are paddle shifters on the steering wheel for manual shifting. The manual shift action is very good for an automatic, although it doesn't totally eliminate slushiness. According to Mercedes-Benz, the transmission adapts to the driver. Among our different drivers on staff, we didn't notice it change, but that may just prove it works exceptionally well.
The Airmatic suspension is a tech feature we really like in this car. First of all, it lets you choose between comfort and sport settings, making a noticeable difference in ride quality. But even better, it does an excellent job of keeping the car from wallowing in corners by counteracting body roll, and that's saying a lot, given the size of this sedan. Although Airmatic suspension and paddle shifters for the transmission give the S550 some sporting characteristics, the steering is aimed much more toward the luxury side of things. The wheel turns too easily, and offers little feedback about the road.
The 2009 Mercedes-Benz S550 goes for a base price of $86,950, putting it squarely in luxury sedan territory. Our particular model came with about $20,000 worth of options, the most interesting from a tech standpoint being the Active Body Control system, for $3,960; the Premium package, adding the massage seats and night vision, for $4,990; and the adaptive cruise control package, which includes the blind-spot system, for $2,880. Fortunately, the navigation system and stereo come standard. Other options on our car, along with the $1,000 gas guzzler tax and $875 destination charge, brought our total up to $109,150.
Although we found some issues with the S550's tech, it still earns a good rating for its cabin gadgets because of some of its driver aid features, such as the blind-spot warning system and night vision. The performance rating is buoyed by tricks like the Airmatic suspension, but dragged down by the fuel economy. It earns good marks for design, helped long by its stylish exterior, clean interior, and easy-to-use COMAND interface.