Wednesday, April 14, 2010
Courtesy of Edmunds Inside Line
Having jumped into thousands of new cars over the course of nearly three decades, it isn't often that you're hit with a car so unfamiliar that it takes you a full minute to figure out how to just pull out of a parking spot. Encountering the 2007 Mercedes-Benz S550 for the first time requires a recalibration of the "been-there, done-that" attitude and an appreciation of the fact that some people are still thinking hard and long about the nature of the automobile and where it's going.
To begin with, the new 2007 Mercedes S550 is without a conventional shifter. Selecting "Park," "Drive" and "Reverse" on the seven-speed transmission — that's right, seven — is the work of a tiny stalk to the right of the mighty steering wheel. The parking brake function has also been reassigned to a smallish paddle to the left of the wheel. No more ratchety E-brake noise on engagement. Instead, a solenoid somewhere opens a circuit and the parking brake is applied by silent electronic gremlins.
In the center of the console where you expect to find the shifter, you see instead a machined aluminum knob that acts as one of the four interfaces to what Mercedes calls its COMAND system, short for "Cockpit Management and Data System." The push-and-turn knob is actually a computer mouse that activates menus that appear on the 8-inch thin-film transistor color display screen in the center of the dash. The mouse/knob navigates you through the screen menus to control the audio system (AM/FM, weatherband, optional satellite radio, CD, MP3 or DVD audio, PCMCIA memory card slot and iPod docking), some seat functions like dialing up the aggressiveness of the seat massage feature, the navigation system, the telephone and address book, and a number of vehicle functions like the security system. Sitting above the mouse is an ellipsoid pod that opens up clamshell fashion to reveal the phone keypad.
Thankfully, the future comes equipped with backup systems, workarounds and alternatives. The mouse is only one of four ways of accessing frequently used features. There are a) conventional buttons that will activate functions directly, b) switches on the steering wheel and c) the voice control system if you get lost in the Matrix and start screaming for your controller to get you back to the real world. And no one would blame you for screaming. Learning to navigate all the systems is a little like getting lost in a house of mirrors. You find what looks like a way out and keep running into yourself coming the other way.
No thanks, I'll ride in the back
While the driver and front passenger can have fun pushing buttons, the rear occupants live in a limousinelike cocoon of comfort. They have their own fixed-glass moonroof, power-operated sunshades for the side windows and rear glass, climate controls, flip-down center console, power seats and enough head-, leg- and elbow room to qualify for a separate ZIP code.
No joke, you can put on a motocross back there. Or at the very least a Security Council meeting. And, of course, it's all done up in leather, highly polished wood and triple-chrome control buttons.
Maybe the two coolest electrogizmos on the S550 are the Distronic Plus adaptive cruise control system and the Night View Assist system. The easiest way to describe the Distronic Plus is to call it a cruise control with a tractor beam function. Once engaged at your chosen speed, a couple of radar beams scan the road ahead. If you're closing in too quickly to the car in front of you, the Distronic system will decelerate, and brake if necessary, to keep you at a safe distance. If you're approaching at a dangerous speed, you'll also get an audible signal to wise up and check your environment. If the car ahead accelerates, Distronic will also accelerate to match the car's speed right up to your preset limit. Granted this is a great safety feature but it also provides loads of entertainment on freeways and city streets. You find yourself playing chicken with the digital domain.
The other very cool feature is the Night View Assist. Unlike most automotive night vision systems that amplify ambient light levels, this system throws out its own infrared light beam. Two beams actually, one from each headlight assembly. The result is captured by an infrared camera mounted in the windshield and displayed on the instrument panel. The black-and-white video image of what's ahead replaces the digital speedo in the IP. There's something mesmerizing about that image. It's like being part of your own police chase or watching an Italian neo-realist film.
Enter the bomber
We were so impressed with the level of tech in the S550 we decided to solicit comments from someone who deals with some of the most advanced hardware on the planet on a daily basis. Our candidate was Craig Bomben, call sign "Bomber." He's a test pilot at NASA's Dryden Flight Research Center at Edwards Air Force Base. Bomben flew combat missions in a Hornet during the first Gulf War and for him, dealing with electrowizardry holds more than a passing intellectual interest. He's out there at the radical fringe of technology separating wheat from what can get you shot down in combat.
The first thing that impressed Bomben was the S550's buttery-smooth power delivery and the massive torque. This is M-B's first use of its new-generation V8 engine family that features four valves per cylinder, variable valve timing and a lightweight crankshaft assembly. This engine and transmission combination sets a new benchmark for smoothness and rapid-onset power delivery. Conventional metaphors like "turbine" or "gyroscopic" smoothness just aren't up to the job of describing this engine adequately. Maybe greased pigs on a waterslide or Vaselined eels wrestling in liquid Teflon.
In testing, the 5.5-liter V8 with 382 horsepower and 391 pound-feet of torque propelled the 4,270-pound S550 to 60 mph in 6.1 seconds. The quarter-mile flew by in 14.2 seconds with a trap speed of 101 mph. The quickest runs were accomplished by letting the engine and seven-speed transmission do all the work. Manually shifting by means of the steering-wheel-mounted shift buttons actually produced slower times, an indication that the shift algorithms have been massaged as much for speed as smoothness. In real-world driving on flat terrain, the engine is barely ticking over at 2,000 rpm at 80 mph, thanks to a combination of the 0.73-to-1 top gear and 2.65-to-1 final drive ratio.
It's like a G-suit
The S550's 14-way adjustable, leather-trimmed front seats take 2nd place to no one. Not only do they have a nearly infinite combination of adjustments, they also have a heating and cooling feature and what M-B calls a drive dynamic feature plus a massage function. You can choose one of four massage levels from fast aggressive to slow and gentle. Some drivers loved the massage. Others thought it was like accidentally sitting on a live raccoon. The bottom and side bolsters can also be inflated to fit your level of comfort while the active lumbar feature fully inflates and deflates a lumbar bladder twice per minute to give the spine a subtle adjustment.
What knocked Bomben out was the dynamic seat feature that automatically inflates the outside back bolster under G-loading. You can dial up the level of bolster response under cornering from a vertical scale on the digital display by using the mouse. Take the S550 hard into a corner and the bolster cradles up against your back like a comforting hand. As you unwind, the bolster slowly deflates until the next corner. I asked Bomben how the seat compares to the chair in the Hornet and he said, "It doesn't have any adjustment. You get what you get. This seat, fantastic. It's like a G-suit."
As night fell, Bomben activated the Night View Assist and after a few minutes decided that he could learn to drive the S550 without looking out the windshield. "The clarity is terrific. It's better than the NVDs [night vision devices] we use because you don't get big heat blooms on this. Oncoming headlights don't blow out the rest of the field like an NVD would." And in truth, you could drive the S550 entirely through the infrared portal. All it takes is nerves, faith in the hardware and a very understanding insurance agent.
Variable rate helical air
The concept of a truly active suspension system has been something of a Holy Grail for engineers since the invention of the decreasing radius curve. While the S550 doesn't reach for the stars like the old Lotus active suspension trial balloon of decades ago, you'd be hard-pressed to find anything that gets as close.
Conventional springs have been chucked in favor of an Airmatic System wherein four air bellows support the weight of the vehicle. Under lateral weight transfer such as cornering, the outside bellows inflate to reduce body lean by as much as 40 percent. The air is supplied by a compressor that produces 227 psi. A computer activates solenoids to inflate and deflate the springs according to road and dynamic load conditions. The driver can also raise the ride height by 1.2 inches by a button on the dash. At speeds over 68 mph, the ride height is automatically lowered by 3/4 inch and lowered 1/2 inch when the transmission is put into Sport mode. Pushing the air button repeatedly won't make the S550 buck like a low rider. We tried.
The suspension architecture is an impressive four-link front suspension and five-link rear. Bomben remarked on the S550's rapid turn-in and astonishing agility in corners. "It feels like a car that weighs a lot less." Mercedes' Electronic Stability Program (ESP) intuits the direction the driver wants to go and where the car is actually going. Using a sensor array that measures steering angle, yaw rate, G-load and wheel slippage, ESP will detect under- or oversteer conditions and apply the outside or inside brakes to maintain the intended direction of travel. On the skid pad, all that glorious hardware conspired to pull 0.83g. Not that long ago, a number like this was the exclusive domain of thoroughbred sports cars.
This latest version of ESP also monitors windshield wiper activation. When the wipers are on, the system automatically and imperceptibly applies the brakes every few seconds to wipe water off the rotors. This helps maintain full braking ability if it's needed. We clocked an impressive 122.7-foot 60-mph-to-0 braking distance.
The stopping power of the massive four-piston front calipers clamping against 13.8-inch rotors and single-piston rear calipers on 12.6-inch rotors is further assisted by M-B's BrakeAssist system. When the system senses faster-than-usual brake application, the brake booster automatically applies maximum braking effort even if the driver doesn't. It also ties into the Distronic system to determine if a collision is in your immediate future and applies the brakes accordingly.
Ejection not an option
When the question of safety came up, Bomben explained that the measure of last resort in a fighter is to abandon ship and float to earth. No such option is available in the S550. At least not yet.
What the S550 does provide is an eight-bag system that includes dual front bags, four side-impact bags (two for the front and two for the rear), two window curtain airbags, seatbelt pre-tensioners for the front and outboard rear passengers and M-B's legendary cabin structure designed to reduce deformation in a collision. When deployed from the headliner, the window curtain airbag is a full 6 feet long, 14 inches in height and 2 inches thick. In its testing, M-B claims a 90-percent reduction in forces likely to cause head injuries in a side impact.
When we sat down for a debriefing that evening, Bomben summed it up by calling the S550, "The most technologically advanced car I've ever driven."
All we can say is "Ditto." By any measure of performance, luxury, safety and sheer technological prowess, the new M-B flagship has set a new standard. There's simply nothing else like it. At least, that is, until next year. That's when we can expect to see the V12 bi-turbo S600 with 500 hp. Until then, the 2007 Mercedes-Benz S550 will just have to do as the world's new benchmark.
Saturday, April 10, 2010
Courtesy of Car and Driver
This new big hybrid from Lexus is deceptively fast. When you floor the gas pedal, the tach needle flicks almost instantly at the bidding of the continuously variable transmission to 6000 or more rpm, a point at which the new 5.0-liter V-8 pumps out about 389 horsepower. This is seamlessly supported by a 221-hp electric motor, and together the two machines send 438 horses to all four wheels through a Torsen center differential.
Because the transmission is stepless and the two motors are so quiet in operation, the sensation is one of eerie understatement as the 5220-pound sedan hurls itself down the road. Lexus proudly claims a 50-to-70-mph time of 3.5 seconds, and we beat that by 0.4 second at the test track. We also beat the company's 0-to-60-mph forecast of 5.5 seconds by a 10th and matched its quarter-mile claim of 13.8 seconds. All these results are significantly quicker than those recorded by the Lexus LS460L, which was 500 pounds trimmer when it was tested for our January 2007 issue.
The fuel consumption should be about the same as the LS460L's — which requires 6.2 seconds to hit 60 mph. Under the 2008 EPA testing regime, the LS600hL is rated at 20 mpg city and 22 highway. We estimate that for 2008 the LS460L will have a rating of 17/25. More telling is that our observed consumption with the LS460L was 13 mpg, whereas the LS600hL returned 20 mpg during its week-long visit with us.
Lexus claims this car has V-12 performance with V-8 fuel consumption, and it's hard to argue with that comparison unless the V-12 in question is in a Mercedes-Benz twin-turbo model, and in that instance, Lexus should expect to get its butt kicked.
This new Lexus hybrid is extraordinarily quiet, with particular attention paid to suppressing noise wherever it's found. There are additional insulators around the V-8's cylinder-head covers. The inverter has a reinforced case to reduce the high-frequency vibrations these devices usually emit. And there are myriad other techniques and materials used to bring noise levels down to about half of those found in other luxury cars, according to Lexus's measurements. (We tested a prototype, so we'll have to wait for a production-car test to verify this claim.)
The company also paid extraordinary attention to safety in the 600, adding advanced precollision with brake activation to the extensive array of safety mechanisms. This system detects objects, determines the likelihood of a collision, and then applies the brakes up to 40 percent of maximum force without any action by the driver.
Along with frugality, a SULEV emissions rating, and the massive elastic surge of acceleration, the 2008 LS600hL proclaims its unique status with blue-tinted badges and that proud (and long) trunklid insignia. Will that be enough to justify the price premium? We — and Lexus — are betting it will.
VEHICLE TYPE: front-engine, 4-wheel-drive, 5-passenger, 4-door sedan
ESTIMATED PRICE AS TESTED: $115,000 (estimated base price: $110,000)
ENGINE TYPE: DOHC 32-valve 5.0-liter V-8, 389 hp, 385 lb-ft; DC permanent-magnet electric motor, 221 hp (battery limited to 49 hp); combined system, 438 hp
TRANSMISSION: dual-range continuously variable automatic
Wheelbase: 121.7 in Length: 202.8 in Width:73.8 in Height: 58.3 in
Curb weight: 5220 lb
C/D TEST RESULTS:
Zero to 60 mph: 5.4 sec
Zero to 100 mph: 12.4 sec
Zero to 110 mph: 14.8 sec
Street start, 5-60 mph: 5.7 sec
Standing ¼-mile: 13.8 sec @ 106 mph
Top speed (governor limited): 130 mph
Braking, 70-0 mph: 171 ft
Roadholding, 200-ft-dia skidpad*: 0.75 g
2008 EPA city driving: 20 mpg
C/D-observed: 20 mpg