The Good: The tech in the 2009 Mercedes-Benz SL550 stands out for its adaptive cruise controls and active suspension, which keeps the car flat in corners. The stereo sounds very good and offers good iPod integration, and Bluetooth cell phone integration is up-to-date. The Bad: The plastic switchgear for the car system's interface looks cheap and doesn't work all that well. The navigation system is devoid of modern features. The Bottom Line: The 2009 Mercedes-Benz SL550 is a big, expensive roadster with some nice aesthetic touches. It has practical features here and there, but this car is more about the statement it makes when you roll up to a restaurant or movie premiere. Photo gallery:2009 Mercedes-Benz SL550Maybe we've been driving too many very nice cars lately, but the 2009 Mercedes-Benz SL550 didn't excite us much when it arrived in the garage. It's hard to follow acts like the Maserati GranTurismo and the BMW M6, and we tend to like shorter, more nimble sports cars. But the SL550 won us over with its handling on winding mountain roads and its striking looks with the sun blazing overhead and a nice ocean-scape in the background. We were also prepared to be disappointed in the car's cabin electronics when we saw the old-style Mercedes-Benz interface, a plastic OK button surrounded by four directional buttons. But delving into this system, we discovered updated electronics behind the rather poor front, including a hard drive-based navigation system, iPod integration, and Bluetooth cell phone support. Test the tech: Nav-off We put Mercedes-Benz's new navigation system to the test by pitting it against the Garmin Nuvi 880. Generally, automakers are at a disadvantage over consumer electronics companies due to the difference in product cycles. A car model may be out for 5 years before it gets an update, while a portable GPS device might get displaced in six months by a newer model. And even though the system in the 2009 Mercedes-Benz SL550 is new, the car still had to go through a couple years of development time. It seemed like the Nuvi 880 would have no problem beating the Mercedes-Benz system. Both navigation systems show similar route-guidance graphics.For our first test, we used the map input function to choose a location on one of our favorite mountain roads, Highway 9 heading down to Santa Cruz from Skyline. On the SL550's system, we had to put the system into map-entry mode, then use the directional buttons to scroll the map south and west from our current position. The large screen helped us keep an idea of where we were scrolling, and the hard drive refreshed the map quickly so we didn't have to wait for it to redraw. The Nuvi 880 uses a touch screen, which we had to continually drag south and west. The smaller screen made this task more difficult, but it also refreshed quickly. The Mercedes-Benz system had the advantage here. The route was easy, but the Mercedes-Benz calculated it just a little faster than the Nuvi 880 did. Both GPS devices offered good graphics to display upcoming turns, but the Nuvi 880 was able to read out the names of streets, and also showed how many miles to the next turn, something missing in the SL550. We like the text-to-speech functionality of the Nuvi 880, so give it the advantage for route guidance. We tried a few locations from both systems' points-of-interest databases, and immediately found that the Nuvi 880 was fuller than the SL550's. For example, it was easy to find a Home Depot hardware store with the Garmin, but the SL550 doesn't offer all shopping locations. As it was lunchtime, we settled on a local fast food place, which both systems were able to pinpoint. Each calculated different routes, but they had the same pros and cons. Just for its bigger points-of-interest database, the Nuvi 880 gets an advantage. We get a little crazy and add a third navigation system to our setup.For our final test, we added the TomTom Go 930, as we happened to have one on hand. With all three nav. systems running, we, of course, felt like total dorks, but programmed in the address for CNET headquarters anyway. The street address was easiest to enter with the SL550's system, as it had predictive text entry, not offered in the Garmin or TomTom. The Garmin was most optimistic about our ETA, while the TomTom suggested the trip would take longer. But none of the system's ETAs were anywhere near accurate, as there was a big traffic snarl when we hit San Francisco. Both the TomTom and Garmin have traffic capability, which we hadn't connected, while the SL550 doesn't, giving the advantage to the portable devices. In performance and interface usability, we felt the SL550 had the clear advantage, but the portable systems both offered more fringe benefits, such as extra points of interest, traffic, and text-to-speech. Route guidance was pretty comparable between the systems. In the cabin The white leather and wood trim in the cabin of the 2009 Mercedes-Benz SL550 gives the car an appropriately luxurious look, but we were thrown off by the plastic switchgear for the cabin electronics and the decidedly cheap feeling of the climate controls. Our test car came with Mercedes-Benz's Air Scarf system, which blows warm air around your neck so you can drive with the top down in colder weather. But it didn't seem to work as well as that same system in the Mercedes-Benz SLK350 we tested previously, which might have to do with the cabin configuration. These vents blow warm air on your neck, making cold weather drives with the top down comfortable.Likewise, our SL550 came with massage seats, but they merely pulsated the lumbar support. The massage seats in the Mercedes-Benz S63 AMG worked much better. (And yes, we do feel like complete jerks for complaining about the quality of massage seats.) The retractable hard top is very nice, although it does compromise the trunk space. There is also a roll bar that can be raised when the top is down. Ours had a mesh windscreen attached to it, but as we couldn't see through that windscreen, we tended to leave the roll bar down, deciding, instead, to avoid flipping the car. We discussed some attributes of the navigation system above. The map resolution is a decided improvement over earlier Mercedes-Benz systems. Beyond that, though, there's nothing special about this system. It does its job well enough, but gives no frills, such as multiple waypoints, traffic reporting, or a comprehensive points-of-interest database. Given that the navigation system uses a hard drive, we would expect the audio system to offer onboard music storage, ripping CDs from the car's disc changer. But that feature didn't seem to be available, although this omission might have to do with our pre-production test car. For music sources, the car offers a six-disc changer that can read MP3 CDs, Sirius satellite radio, and full iPod integration. There is also an SD-card slot above the CD slot. As in other cars with this mix of audio sources, we preferred the iPod due to the fact we could select music with more flexibility than we could on CD or SD card. You can adjust Bass, Treble, and Balance with the audio controls, but there is no Fader, as the car is only a two-seater.The Harmon Kardon Logic 7 sound system did an excellent job of making our music sound great. We could hear individual instruments very well, and there was richness and texture to the overall sound. Although you can't see most of them, there are eight speakers around the cabin, including a center fill and a subwoofer. Although this amount sounds minimal for a high-end audio system, the speakers only have to cover two seats. The final piece of cabin tech worth mentioning is the adaptive cruise control. We tested it out by setting a speed of 75 miles per hour on the freeway. The SL550 caught up with slower moving traffic, then dutifully matched their speed and maintained its following distance. The system worked well in responding to cars cutting in front of us, never forcing us to put a foot on the brake. But we had difficulty adjusting the following distance, which seemed to default to 100 feet, a little short at freeway speeds. Under the hood Our initial drives in the 2009 Mercedes-Benz SL550 left us with the impression that, although powerful, the car didn't have much in the way of sports car chops, instead offering a fine luxury ride. We realized the wrongness of our first impression as we got the car moving fast over winding roads. The SL550 comes with Mercedes-Benz's Active Body Control (ABC), which normally reduces body roll by 68 percent through the clever use of hydraulics. Put it in Sport setting, and body roll gets reduced by 95 percent. We could feel the stability of the car as it went into a corner, the body remaining level as we put the wheel around. This system also reduces dive and squat, preventing the front wheels from lifting when you put on the power. Although ABC keeps the car from feeling terribly exciting, the fact that it stays under control is a more than worthwhile trade-off. The ABC button lets you put the active suspension in sport mode, and a button at the top of the gate changes the transmission between Comfort, Sport, and Manual.We've driven plenty of Mercedes-Benzes with this 5.5-liter V-8; since its development for the S-class it has become the standard big car engine for the company. In this application it puts out 382 horsepower at 6,000 rpm and 391 pound-feet of torque between 2,800 and 4,000 rpm. That power gets the SL550 to 60 mph in 5.1 seconds, according to Mercedes-Benz, with a top speed limited to 155 mph. We had no difficulty tapping that power and making the big roadster leap forward. The engine is mated to Mercedes-Benz's now-standard seven-speed automatic transmission. The company has put a lot of fine-tuning into this transmission, making it perform as close to a manual as possible. A button at the top of the gate lets you choose Comfort, Sport, and Manual modes. As would be expected, Comfort is fairly dull, but Sport kicks in a program that aggressively downshifts, and will keep rpms high when you handle corners. We quickly learned how to take advantage of the transmission by applying plenty of brake before the corner to activate a heavy downshift, then hitting the throttle on the way out of the turn to hold the lower gear. In manual mode, the transmission shifts quickly and keeps the gear you select. You can choose gears by moving the shifter left and right, or with the paddles mounted to the wheel spokes, using the right one to upshift and the left for downshifts. Not quite F1-style and a little difficult to control with the wheel cranked around, but you should have shifted before the turn. Given the size of the engine, we were expecting dismal mileage. But we ended up with an average of 17.4 mpg for city and freeway driving, right in the middle of the EPA range of 13 mpg city and 21 mpg highway. These numbers aren't great, but not particularly bad for such a big engine. As of this review, the emissions rating was not available. In sum The base price for our 2009 Mercedes-Benz SL550 was $96,775, making it one of the more expensive roadsters around. We added the $3,750 Premium package, which brought in Air Scarf and massaging seats, the $1,950 SL wheel package, which added AMG-style wheels and a sport steering wheel, and the adaptive cruise control option for $2,230. The total for this car, without destination, is up at $104,705. That's a lot of money for a two-seater, but it is a good-looking car, and a convertible. Although luggage room is limited, it also offers a couple of compartments behind the seats, adding a little practicality. The SL550 earns a moderate score for cabin tech. We like the sound of the stereo, and it handles a variety of audio sources. Navigation works well, but offers few features, while the phone system is nice and modern. And it gets a bonus for adaptive cruise control. Its performance is excellent, helped by its active suspension and smart transmission, but we knock it a bit for poor mileage. Design is a mixed bag. We like the car's looks, but that's about it. The electronics interface is fairly poor, and its space limitations are a problem. You could get a couple of convertible Audi TTs for the same price, carry as many people, and probably have more fun.