The Good: The 2008 Mercedes-Benz S63 AMG handles incredibly well for a big sedan and has oodles of power. Its GPS uses high-resolution maps, its stereo system sounds excellent, and it has over-the-top tech like night vision and massage seats. The Bad: The gas mileage on the S63 AMG is pitiful, with our observed average being 13.2 mpg. The Bottom Line: The 2008 Mercedes-Benz S63 AMG defines luxury and performance, offering usable and high-quality cabin gadgets pushed down the road by a powerful, and thirsty, engine. Photo gallery:2008 Mercedes-Benz S63 AMGWhen Mercedes-Benz updated its flagship S-class sedan for 2007, it made the car a technology masterpiece. Now, AMG, the German carmaker's in-house tuner division, turned that car into a performance masterpiece. The 2008 Mercedes-Benz S63 AMG is a big, fast European sedan, the kind of car that makes you feel you should be bombing through the Alps on urgent business in Switzerland. As we drove the car during our test, we found ourselves glancing in the rear-view mirror, looking for the diplomats, or spies, who we knew belonged in the capacious back seat. But the car wouldn't let us glance back for long, as there is too much to pay attention to out in front. The S63 doesn't go slow. On a pleasant cruise down a country road we were surprised to find that what seemed like 45 mph was actually 75 mph, and climbing toward 80. Then there are the electronics, from a lovely navigation display to a stereo system with brain-frying audio quality, which demanded our attention, as well. Oh, and did we mention the massage seats? Yes, the 2008 Mercedes-Benz S63 AMG gets everything, absolutely everything, thrown into it, making it almost perfect. Almost. Test the tech: Knight Rider Among the S63 AMG's many tech features is a very good speech-recognition system. This feature led us to test out how well the car compares with KITT, the car from the television series Knight Rider. And, because the car came equipped with Night View Assist, we put a homonym twist on our test by conducting it at night. The first difference we noticed with the S63 AMG's speech system was that it spoke with a pleasant female voice, rather than KITT's clipped male voice. Our car wasn't as chatty, either, merely advising us on how we could use it to control the stereo, navigation, and Bluetooth telephone system. But it seemed to respond to our commands every bit as well as KITT did with Michael Knight. With these very adjustable seats, Pulse Mode means massage.As we set out after a day in the office on our test, we were feeling a bit tired, so activated the S63 AMG's massage seat, choosing a slow and vigorous pummeling from the seat control menu. It was very invigorating, and a luxury that KITT lacked. We found that our car's entertainment system was every bit as good as KITT's, playing music or video from a six-disc changer, and letting us hook up a video game through RCA jacks in the glove box. When we got off city streets and onto the freeway, we explored the S63 AMG's ability to see and drive itself, as KITT could do. We set our car's adaptive cruise control at 75 mph and took our foot off the gas. The S63 AMG used its radar to track the car in the lane ahead, matching its speed of around 65 mph and maintaining a safe driving distance by operating its own accelerator and brakes. We did have to keep our hands on the steering wheel, which we wouldn't have had to do in KITT KITT is very fast, but so is the S63 AMG. Where KITT has an eight-speed transmission, the S63 AMG has seven speeds. KITT can make it to 60 mph in 2 seconds, where the S63 AMG's 518 horsepower brings it to 60 mph in 4.5 seconds. So we lose a little on the performance side, but we had a good time trying out this power as we barreled down the freeway, then pulled onto a dark, winding mountain road. For this part of the test, we turned on our car's Night View Assist feature, to our knowledge a feature lacking in KITT. Night View Assist uses infrared projectors and cameras to generate an image of the road ahead. With this feature activated, the speedometer, which is actually a video screen, changes to display the forward-looking image. The night vision camera offers a nicely illuminated image of what's out in front of the car.We raced through the dark night, using Night Vision Assist to see what kind of car was up ahead when all we could see through the windshield were a pair of taillights. We also found it helpful because our low beams didn't illuminate enough of the road to show upcoming turns. A glance down at the video showed much more of the road ahead than we could see through the windshield. The S63 AMG handled these corners wonderfully, with no body roll as its tires made a pleasant singing sound. We're pretty sure that the S63 AMG corners better than a 1982 Pontiac Trans Am, the car on which KITT is based. Turning down a less-trafficked road, we switched on our high beams, a feature that KITT surely had. But on our car, the beams swung around as we cranked the wheel in corners, doing a great job of illuminating the direction we wanted to go rather than the opposite side of the road. We felt the S63 AMG compared very favorably with KITT. Oh, there are some things it didn't have, such as a bullet-resistant body. We didn't feel Mercedes-Benz would be too happy if we tried to test that out. Neither does the S63 AMG have a smoke screen, flame thrower, tear gas launcher, or ultramagnesium charges. However, the S63 AMG has the very important quality that it is not fictional. In the cabin When we first opened the door of the 2008 Mercedes-Benz S63 AMG (using a smart key, no button-pushing required), we were impressed by the incredibly clean look of the dashboard. With the car off, the instrument cluster is a black panel and the switch gear is a single row of metal buttons. The front of the console hosts the knob for Mercedes-Benz's COMAND interface and a few more metal buttons. The knob lets you select menu items on the wide-screen LCD mounted at the top of the stack, controlling such features as navigation, audio, and cell phone integration. You can pull up a list of traffic incidents from the navigation system for local freeways and major roads.The navigation system in the S63 AMG runs off of a hard drive, giving it fast response times and enough room to hold very high resolution maps in both plan and 3D views. Unfortunately, none of this hard-drive space is reserved for music, unlike with the Cadillac CTS or Mercedes-Benz's own C300. Also, the maps only show names for every visible street when you are at the highest zoom level. But we were very impressed with the route guidance, which displays helpful graphics on one side of the screen for upcoming turns. Approaching one particularly complex freeway entrance, we were impressed that the graphic showed four turns we would have to negotiate in a short amount of space. The navigation system also incorporates XM live traffic reporting, showing incidents and traffic flow information. But we were disappointed that the car wouldn't proactively warn us about traffic jams on the road ahead of us. We had no complaints about the quality of the audio. This car uses a 14-speaker 600 watt Harmon\/Kardon Logic7 stereo system, which sounds excellent. It's almost too clear, as we heard imperfections in the recordings we listened to. The shriek of a guitar on a White Stripes track was satisfyingly deafening, while bass-heavy tracks delivered a good thump. Even though the car uses XM for its traffic, it uses Sirius for satellite radio. We found it easy to select stations using the unique radio interface with the COMAND system. The six-disc changer, mounted behind a panel in the center stack, plays MP3 CDs and DVDs, with ID3 information for MP3s displayed on the LCD. Another digital audio source can be found in the PC Card slot mounted just below the six-disc changer. We find this choice a bit odd, because PC Cards aren't very common anymore, although you might be able to dig one up that worked as an adapter for SD cards or Compact Flash. The S63 AMG includes Bluetooth for a select list of phones and has a first-rate speech-recognition system. For a long time, Mercedes-Benz restricted its cell phone integration to a hard-wired cradle system, but it fitted a Bluetooth system into the S63 AMG. Unfortunately, we couldn't get this system to pair with our Samsung SGH-D807, which isn't on its list of compatible phones. To check if your phone is compatible, visit the Auto Wireless Solutions Web site. We covered some aspects of the speech recognition system above. This system did a fantastic job of recognizing and responding to our commands, allowing almost normal speech in many instances. We easily set a destination back to our office in San Francisco by spelling out the street name in one string. It also knows the names of satellite radio stations and will play them from a vocal command. The front seats in this car are really incredible. We mentioned the massage aspect above, which lets you choose from four massage types. You can also fine-tune the intensity of the massage for your back and shoulders. But these seats do plenty more. First, they allow a fine degree of tuning to fit their occupants, from extending the seat out, tightening up the sides, and moving the lumbar support. These seats also have a dynamic component, adjusting the side bolsters to support their occupants while cornering. The intensity of the side bolstering can be adjusted or turned off entirely. Under the hood While we've seen most of the S63 AMG's cabin electronics in other Mercedes-Benz models, this engine is something new. We got a special presentation on Mercedes-Benz's AMG tuner division earlier this year, and the chance to drive a number of other AMG models. With AMG cars, the engine is hand-built and signed by the engineer responsible. AMG has been equipping a number of Mercedes-Benz models with the 6.3-liter V-8 used in the S63 AMG. But each car gets its own special tweaking. In the S63 AMG, the engine cylinders have been given a special coating to reduce friction. The seven-speed automatic, currently used in most Mercedes-Benz cars, is tweaked by AMG for faster shifts. AMG engines are works of art, with a badge on top signed by the engineer who built it. As the S63 AMG uses a smart key, you bring the car to life by pushing a button. The engine turns on with an impressive roar before settling down to idling speed. We noticed while driving this car that, under acceleration we could hear the really fine engine note, but while cruising on the freeway sound was deadened, letting us listen to the excellent stereo system without interruption. The transmission can be cycled through three modes with a button on the console: Sport, Comfort, and Manual. Sport holds revs longer than Comfort, while Manual lets you roll your own using the paddle shifters on the steering wheel. When we stomped the gas in Sport mode, we didn't get an immediate rush of speed, although the car picked up quickly, and its 518 horsepower would have kept up that acceleration for a long time. Manual mode was a different matter, letting us hold first gear so the car could leap forward on its 465 foot-pounds of torque. As we threw the car around during out testing, we found that it cornered exceedingly well for a big sedan, maintaining an even keel at speeds that would have many cars off the track. But we had to be wary of the fact that the S63 AMG insulates you from the feeling of speed, so it was often going faster than we would have thought from looking out the windshield. A heads-up display could be useful in this car. Surprisingly, we could even get a bit playful with it, snapping around tight corners and letting the back end get out a bit. We never felt like it was about to fishtail in these instances, with the car maintaining our sense of control throughout. As we powered out of corners, the S63 AMG felt like what it was: a rear-wheel-drive car with lots of horsepower. The S63 AMG uses Mercedes-Benz's standard drive selector, along with paddle shifters for manual control of the transmission.But there is a price to be paid for this type of fun. And in the case of the S63 AMG, it's a very steep price. The car's EPA rated mileage is an awful 11 mpg city and 17 mpg highway, subjecting it to the gas guzzler tax. During our test period, which involved city, freeway, and mountain driving, we saw an average fuel economy of only 13.2 mpg. Although we imagine anyone that can afford this car won't scoff at $80 fill ups, the fuel economy affects the range, letting you travel maybe 350 miles before you have to stop. Likewise, it only meets California's minimum LEV II standard for emissions. The S63 AMG features the best Mercedes-Benz safety tech, including its Pre-Safe system, which uses the front radar to detect imminent collisions. During our drive, we experienced the first stage of this system on a few occasions. As we rolled forward toward another stopped car, the S63 AMG gave an audible signal to let us know we should hit the brakes. If we hadn't done so, it would hit the brakes for us. If it sensed that even braking wouldn't stop the collision, it would tighten the seat belts and take other measures to protect the occupants. In sum The 2008 Mercedes-Benz S63 AMG is an example of what you can get if money is no object. The car bases at $127,000, which includes a lot of the gear mentioned above, such as the Harmon\/Kardon stereo and the navigation system. But we added a few other high-tech options, starting with the adaptive cruise control for $2,870 and Night View Assist for $2,090. An AMG performance package gave us 20-inch wheels and adjusted the top speed governor to 186 mph, all for $7,000. The rear seats got eight-way power adjustment and their own sunroof for $3,930. Along with a $775 destination charge and $3,000 gas guzzler tax, our total came out to $146,665. This car came awfully close to earning a perfect score from us. For design, we really like its looks, with its pronounced wheel arches almost looking like classic fenders and its general big European sedan style. And the interior is just a nice place to be, with its clean dashboard design. For cabin electronics, we might have liked an in-dash music server or an iPod connector, but the lack of those was completely made up for by the over-the-top features, such as the massage seats and the adaptive cruise control. And we can't deny how good the stereo sounded or how well the speech recognition worked. In the performance department, again, perfect, except for that little problem of terrible fuel economy. The only car we've reviewed with which we can compare the 2008 Mercedes-Benz S63 AMG is the 2008 Lexus LS 600h, a car that may fall a little short in acceleration, but gets 8 mpg better than the S63 AMG.