Global Vehicles
High-technology VW Phaeton
 The Phaeton is a large luxury car with technology that includes the choice of a W12 gasoline engine or a V10 turbodiesel, taking VW into a new market sector. |
The distance in terms of technology, design, quality, capability, and price from the air-cooled Volkswagen Beetle to the new Volkswagen Phaeton—Project D1—is almost beyond measure. The Phaeton, first seen as a concept at the 1999 Frankfurt Motor Show, made its debut in production form at this year's Geneva Motor Show. Nothing like it has been seen before from VW. It is a showcase of automotive technology; even the Dresden "Transparent Factory" where it is built involves a new production concept, with components delivered by tram. It will compete with many of the world's prestige cars, including the Mercedes-Benz S-Class and the latest-generation, high-technology BMW 7 Series. It may also be a pointer to the sort of technology and systems that will be incorporated in the new midsize Bentley that is now under development.
The Phaeton range leader will have a 6.0-L, 309-kW (414-hp) W12 gasoline engine, air suspension, 4Motion all-wheel drive, and the sort of draught-free air-conditioning system that (if it works as described by VW) the automotive industry has been awaiting for decades. Other engine choices will eventually include a 3.2-L V6, 4.0-L W8, and 5.0-L, 230-kW (308-hp) V10 diesel—the latter claimed to be the world's most powerful passenger car diesel. Its maximum torque is 750 N•m (553 lb•ft). The car features a six-speed automatic.
 The interior of the Phaeton features a new air-conditioning system with vents that open and close automatically. |
Five years in the making, the Phaeton is very much the special project of retiring VW Group Chairman, Ferdinand Piech. Its dimensions are similar to those of its main rivals with an overall length of 5060 mm (199 in) and a width of 1900 mm (75 in). To keep mass around 2300 kg (5070 lb), aluminum is used for doors, trunk lid, and hood. VW has focused on advanced manufacturing techniques such as doors produced using a laser-welded die-cast aluminum process. The doors are manufactured to a rigidity that far exceeds any structures previously available in a road car, claims VW. The car will be built in Dresden, eventually at a rate of 100 units per day. The company has invested DM365 million in the facility.
With regard to the suspension system, the objective was to produce a system that would meet the most exacting demands in terms of ride comfort and dynamic driving, according to VW. Air-spring systems with regulated damping are said by the company to be excellent for this. Vehicle height is maintained regardless of load, although the driver can manually override the setting. The air springs automatically adapt the (mapped) damping rate to load. At speed, the Phaeton settles lower to improve aerodynamics and reduce the center of gravity to enhance stability.
 Phaeton testing on ice. |
The system comprises four air spring struts on the front and rear axles, an air-supply unit, pressure accumulator, control unit, four level sensors, two body accelerometers on the front axle and one at the back, and a total of five air lines. The air spring modules have what VW describes as "a completely new type of spring bellows." Low spring rate is provided by "an additional volume and by a special piston shape." The special design and location of the suspension strut support bearing (upper connection to the body) ensure that transverse forces are kept away from the dampers. Twin-tube, gas-filled suspension dampers are fitted.
Data exchange with other parts of the car, including engine and gearbox, is via a CAN bus. The driver has a control placed behind the gearshift for ride level and suspension damper regulation. The car has three height settings: Standard; Raised, 25 mm (1 in) above Standard; and Lowered, 15 mm (0.6 in) less than Standard, which is automatically activated at high speeds—which VW cites as 160 km/h (100 mph). The damper mapping covers Basic, Comfort, Sport, and Sport2 settings. Other elements of the suspension include a four-link setup at the front and a trapezium-type rear.
 VW claims the Phaeton's 5.0-L 230-kW (308-hp) V10 is the world's most powerful passenger car diesel. |
The Climatronic system provides four-zone control, including for passengers on the right and left of the rear seats. Air is fed through automatically opening and closing vents. The system has a humidity control to automatically reduce the likelihood of window misting. Climatronic is complex and uses 25 electric positioning motors. One of the main aims of the system is to create a draught-free airflow, so blower vents initially cool the car's interior, then close to be hidden behind wooden panels, after which a "ventilation strip" gives global air-conditioning. The rear system has a multi-functional distributor into which distribution boxes are fitted. Seven sensors look after the level of individual air temperature zones.
- Stuart Birch
Mercedes-Benz SL 55 AMG
 Aerodynamic aids on the supercharged Mercedes-Benz SL 55 AMG are discreet.  |
The demand for ever higher car technology to provide ever greater performance continues apace, despite extensive speed limits on roads around the world. When the new Mercedes-Benz SL was unveiled last fall, DaimlerChrysler announced that an even more powerful version of the 225-kW (302-hp) SL500 would be available in 2002. Now it has arrived. The SL 55 AMG's extensively modified and supercharged 5.4-L V8 engine produces 350 kW (469 hp) and a remarkable 700 N•m (516 lb•ft) of torque. It is the most powerful of all Mercedes' passenger cars. At tickover and low engine revs, the sound from the AMG's quadruple tailpipes is fairly muted, but under full-throttle acceleration, it becomes a very loud growl absolutely in keeping with the car's performance. The car is, of course, within the 74 dB(A) pass-by noise limits. There is some supercharger whine, too, which is wholly in keeping.
Overall, the aural elements of the AMG match the performance figures, which include a 0-100 km/h (0-62 mph) time of 4.7 s, with 200 km/h (124 mph) reached in just over 15 s. Top speed is electronically limited to 250 km/h (155 mph), but it is understood that the car has been track-tested at speeds above 300 km/h (186 mph). The SL 55 AMG's brakes are even larger than the already massive units fitted to the regular SL. Its chassis electronics are thoroughly comprehensive and the transmission includes manual selection via steering wheel buttons.
The new SL is a remarkable technology tour de force, and the AMG version has all that technology (including folding hardtop)—and more. DaimlerChrysler decided, even at the concept stage of the new range—five years before it was revealed—that there should be an ultra-high-performance AMG version. The regular SL500 is already a very powerful car in its own right, but the company wanted the AMG car to be significantly more so, and with a clear identity, although aesthetic differentiation would be relatively modest. So while the SL 55 AMG gets many subtle changes, this car is really about its engine.
 Manual gearshift buttons on the SL 55 AMG are positioned behind the upper spokes on the steering wheel: right for upshifts, left for down. |
Almost all the mechanical components of the SL500 engine were modified to create the 55 AMG power unit. Although the AMG's engine is up from the SL500's 5.0 to 5.4 L—the stroke is longer by 8 mm (0.31 in) at 92 mm (3.62 in)—it is the use of a supercharger that really transforms its output. Belt-driven and developed specifically for the SL 55 AMG, it is a screw-type unit, positioned between the cylinder banks, and directly linked to the crankshaft. Its aluminum compressor screws are Teflon-coated and rotate at a maximum 23,000 rpm (engine speed is 6500 rpm). It works on the Lysholm (interlocking helical rotors) compressor principle. DaimlerChrysler says it achieves about 30% more charge pressure than other comparable belt-driven systems. Maximum charge pressure is 80 kPa (11.6 psi). The engine management controls the supercharger's use, responding to both speed and load. The supercharger module also houses an intercooler, an air-to-water system that takes heat from the compressed air and transfers it to the coolant. A pump allows the water to flow through a special low-temperature cooler, which is located in the cooling module between the air-conditioning condenser and the radiator. The system is independent of the engine's coolant. AMG also modified the SL500's oil-cooling system, fitting a separate oil cooler behind the car's front apron.
The fuel system is also special to the SL 55 AMG and, for the first time in a Mercedes passenger car, it is computer-controlled. Other changes from the SL500 engine include modified crankshaft bearings of a more durable material; pistons using "a special material"; modified oil sump with catch tray and more powerful oil pump; cylinder head changes with optimized intake and exhaust ducts; camshafts with longer valve-opening times; valvetrain with double spring assembly; and a more comprehensive engine ECU, which includes control of electronic maps for the compressor.
DaimlerChrysler describes the SL 55 AMG's exhaust system as being just as sophisticated as its supercharger. It uses twin 70-mm (2.76-in) pipes. There are two firewall catalytic converters with "extremely" thin-walled ceramic monoliths, plus two metal catalytic converters underbody. Four lambda probes are fitted, and the car meets 2005 EU-4 emissions legislation. The system uses two center and two rear mufflers. DaimlerChrysler explains that to achieve the thoroughly sporty exhaust note from the car's four tailpipes, a permanently open connection links the two exhaust pipes. The system uses a similar principle to an organ pipe, depending on the effect of varying dynamic waves to help with sound tuning. This contributes to the achievement of the desired sound quality on wide throttle openings at high revs without compromising pass-by noise limits.
 The SL 55 AMG's 5.4-L V8 engine has a supercharger and intercooler positioned between the cylinder banks. |
Although the five-speed auto plus manual transmission fitted to the SL 55 AMG is almost the same as that used in the SL500, it also includes manual shift buttons. These are positioned behind the steering-wheel rim to be operated by the fingertips rather than at the front of the wheel operated by the thumbs, as with some other applications. DaimlerChrysler did consider paddles but opted for buttons. The result is highly effective and facilitates a natural movement: right button for upshifts, left for down. A switch on the center console activates the system's use. If maximum permitted revs are reached in any of the four lower gears, an upshift occurs automatically. When the car comes to a standstill, first is automatically selected. The selector lever also offers a manual gear select facility, and there is an automatic winter mode.
The SL 55 AMG benefits from the raft of high-tech chassis systems fitted to other upmarket Mercedes models, including Sensotronic Brake Control (SBC), Active Body Control (ABC), and Electronic Stability Program (ESP). Algorithms have been changed where necessary in keeping with the AMG's enhanced performance potential. In keeping with other SL varieties, the 55 AMG has an online facility to calculate weight, which is allied to the ABC. The AMG version of the SL also has dedicated suspension struts and stiffer dampers. Other chassis changes include more powerful brakes with internally ventilated and perforated discs: 360 mm (14.2 in) at the front and 330 mm (13 in) rear. The front brakes have eight-piston fixed calipers with four pads, the pad face double that of the SL500. Multi-spoke wheels are 18 in (8.5J at the front, 9.5J at the rear); front tire size is 225/40R 18, rear 285/35R 18.
Aesthetic changes for the AMG compared to the SL500 are relatively discreet. The deeper front apron with expanded metal grill shields the oil cooler, there are modest sideskirts, and at the rear, a grill echoes that at the front and contains the four oval tailpipes. The interior includes more prominent seat side bolsters than those fitted to the SL500. An AMG design is used for seat covering, Alcantara trims the instrument cluster, the instruments have an AMG design, and aluminum—rolled and anodized to form a sand-cast effect—is used for some interior detailing and components.
- Stuart Birch
