- Mar 20, 2009
Porsche Panamera: In-depth tech briefing and first ride
Porsche Panamera - Click above for high-res image gallery of tech briefing
The new Panamera is without doubt one of the two most controversial vehicles ever to come from Porsche, the other, of course, being the Cayenne. While traditional Porsche fans howled at the idea of an SUV coming from the "sportscar maker," this time around, the problem is not so much the premise of a four-door, four-passenger Porsche, but rather the car's styling.
Porsche is no stranger to controversy surrounding its new models. In fact, the German automaker seems to thrive on the divisiveness. Some of the cars that purists have complained about most bitterly have been among its best sellers. Much of the same whining heard about the Cayenne and Panamera accompanied the introduction of the front-engine, water-cooled 924 and 928 in the '70s, and to a lesser extent, even the transition of the 911 from air to water cooling.
The Panamera won't be shown publicly until the Shanghai Motor Show next month, but Porsche invited several dozen international media to its Weissach R&D center this week for a workshop on the technical details of the Panamera, and we were along for the ride. Read on to learn more about what makes the Panamera tick.
All photos Copyright ©2009 Sam Abuelsamid / Weblogs, Inc.
We've been seeing spy photos of the Panamera in camouflage for several years and Porsche released official photos in production form last November. When the production photos appeared, everyone's worst fears about the design seen in spy photos appeared to be true. Instead of the sleek, sloping roofline of competitors like the Mercedes CLS and upcoming Aston Martin Rapide, the Panamera had what looked like an ungainly hunchback.
Of course, Porsche has a long history of designing cars that wouldn't be considered beautiful in the classic sense. Instead, the Germans take the "form follows function" approach. That means engineers determine what they want the car to do and then the designers work around that brief. In this case, the result is that humpback shape on the back half of the car.
Back in the late 1980s, Porsche had plans to build a similar car dubbed the 989. That project was scrapped during the recession at the end of that decade, but the styling concept for that car showed a design that looked much more like the eventual 996 and 997 generation 911s. With a sloping roofline that resembled an elegant four-door 911, this was certainly more aesthetically pleasing. However, rear headroom was severely limited. This time around, Porsche wanted a true four-person grand touring car. Thus, the roofline stays high above the rear seats before dropping off at the back.
When we arrived in Weissach, we were taken straight to the Motorsports Hall. This is the building that normally serves as the final preparation and delivery facility for customers buying Porsche racing cars. During our visit, a row of 911 GT3 Cup cars sat outside the building alongside a trio of Panameras. We immediately swarmed over the new GTs and it was again apparent that the Panamera's design is not shown to best effect in photographs. It still isn't gorgeous in the 911 sense, but is far less homely in person than we imagined.
Climbing into the back seat, it's immediately apparent that the lumpy profile pays off with ample interior room for second row passengers. Compared to the BMW X6 (not a direct competitor, but an interesting comparison in this case), six-and-a-half footers should have no problem, with clearance available even when the sunroof is ordered. The healthy 115-inch span between the axles also means that the Panamera offers plenty of room for the long-legged, as well. After a few minutes checking out the Panamera, we were ushered inside to learn all about what was under the skin.
Porsche provided four tech sessions that we rotated through along with a taxi ride in the car on the track. We began by looking at the body structure. The 195.7-inch long Panamera is a large car, and like any other big, powerful luxury machine, it's packed with hardware and technology. As we've seen over the past two decades, such cars have gotten increasingly hefty with the likes of the Maserati Quattroporte approaching 5,000 pounds. Porsche engineers aimed to keep the Panamera's mass down to something more reasonable, and they seem to have largely succeeded.
The Panamera is certainly no lightweight, but at 3,903 pounds for the base rear-drive, normally aspirated 4.8-liter model, it's lighter than expected. Even the heaviest all-wheel-drive turbo version tips the scales at just 4,344 pounds. The engineers used a mix of aluminum, magnesium, plastic and several grades of steel for the body. Three quarters of the body-in-white mass, including the central portion of the body, is steel. Easily moldable deep drawn steel is used for the side panels and roof, while high strength steel is used for the side rails, rear structure and firewall, with the rest being a mix of multi-phase, stainless and boron steels.
The heavier, stronger steel was kept to areas predominantly within the wheelbase, where it is closer to the car's center of gravity. This helps minimize the Panamera's moment of inertia and aids handling. At the car's extremities, lighter aluminum and magnesium are used. The door structures, front and rear crush structures, front fenders and hood are all stamped, extruded or cast from the light alloy. Magnesium castings are also used for the side window frames and radiator mount.
Looking around the body structure, it becomes clear that engineers have made an effort to remove material wherever it doesn't contribute any function. One clear example is the sides of the engine compartment ahead of the front suspension mounting structure. A typical vehicle would have a solid metal stamping with a plastic wheel well liner bolted behind it. The Panamera just has the wheel liner. Similarly, the aluminum stampings in the doors have been laser cut to remove excess material that doesn't contribute to the structure.
The primary plastic body component is the rear wing, which rises up at speed. It lifts up at 55 mph and tilts to an angle of incidence of -3 degrees. That's enough to trim out the air flow and keep drag to a minimum. As speeds rise above 127 mph, the wing tilts up to a positive 10 degree angle to generate some downforce. Normally aspirated models get a single piece wing while the turbo gets a multi-piece unit. As the turbo wing rises, the upper surface lifts higher, splitting in the middle and extending outward for even more surface area.
Porsche didn't want the Panamera to generate huge amounts of downforce, since that would also increase drag, which they were trying to avoid. However, the turbo generates about 15 pounds of downforce at 155 mph, making it essentially neutral. The normally aspirated cars have a drag coefficient of 0.29, while the turbos come out the wind tunnel at 0.30.
Another area where Porsche has optimized mass is with the Panamera's climate control system. They have devised a four-zone climate control system that uses a single, central core system with ductwork going to each of the seating positions. A four quadrant sun load sensor mounted on the dash measures the angle and intensity of the solar load. This signal is fed into the climate control system to help make the control more efficient.
At launch, all Panameras will be powered by 4.8-liter V8s based on the Cayenne GTS motor. The engine can be had with or without turbochargers. Both engines get direct injection that helps improve power while reducing fuel consumption. The base version spins out 400 hp at 6,500 rpm and a healthy 369 lb-ft of torque from 3,500-5,000 rpm. The force-fed versions add a turbocharger to each exhaust manifold, which boosts the output to an even 500 hp. More importantly for fans of instant thrust, the torque goes to 516 lb-ft between 2,250 and 4,500 rpm.
European buyers will be able to opt for a six-speed manual gearbox on the rear-drive, normally aspirated model. All American Panamera drivers, as well as everyone that gets all-wheel drive or a turbo, will get the seven-speed PDK transmission. This is based on the same dual clutch transmission used in the 2009 911. All PDK-equipped Panameras (meaning all U.S. market cars) will also get an automatic start-stop system, the first automatic-equipped premium car so equipped.
Porsche's engineers have also done some interesting packaging tricks with the all-wheel-drive system. A so-called "hang-on" torque distribution unit is bolted to the back of the gearbox. This electronically controlled clutch pack sends the torque to the front or rear axles as needed. The front differential housing is bolted directly to the side of the block and oil sump. Since the differential doesn't move relative to the center clutch unit, the drive shaft doesn't need any universal joints. The intermediate shaft that crosses through the sump, from the front differential over to the left half shaft, passes a mere 1 mm below the crankshaft bearing cap.
On the lower, left-front side of the block is a variable-vane pump used for steering assist. The pump can be controlled to vary the flow as needed, helping to minimize parasitic losses. Porsche chose not to use electric power steering because the engineers were unable to achieve the steering feel they wanted at the cornering forces of which the Panamera is capable – a hydraulic system ended up providing a more natural feel to the steering.
Speaking of dynamic behavior, the Panamera has some very interesting hardware on board, as well. The suspension at both ends of the car is mounted to a rigid cast aluminum sub-frame that helps maintain the relative position of the corners to each other. The front axle uses upper and lower control arms with springs mounted concentrically with the damper. At the rear, multiple links manage the kinematics of the wheels and the springs are mounted separately from the dampers.
The standard configuration employs coil springs. Turbo models replace the coils with air springs that are also optionally available on the normally aspirated models. Each air spring has a valve that controls the volume of the spring. The valve is closed in Sports Plus mode, cutting off half the volume of the spring and increasing the effective spring rate. Activating the Sport switch on the center console tightens up the adaptive damping system, which uses additional accelerometers, curve inclination and wheel motion sensors to manage the dampers at each corner.
With the Porsche Dynamic Chassis Control, active anti-roll bars are included. Anti-roll bars are simply torsion bar springs tying the corners together with the body. The amount of body roll is managed by the spring rate of the bar. Actuators on both front and rear bars adjust the effective spring rates and, in combination with the adaptive damping and dual volume air springs, the Panamera can corner almost completely flat even at high lateral acceleration rates.
An important element of dynamic behavior is being able to dissipate speed. Here again, the Panamera seems to have the goods. All variants get mono-block calipers at all corners with six-piston units up front and four-pistons on the back. The non-turbos get 14.2-inch front and 13-inch rear steel rotors with the turbo upping those dimensions to a massive 15.4 and 13.8 inches. In typical Porsche fashion, buyers can also opt for the carbon ceramic composite rotors if they plan to drive their car particularly hard. In total, Porsche says its Panamera Turbo offers over 1,700 hp of braking power, so stopping consistently shouldn't be a problem.
Many high performance, all-wheel-drive cars are getting some form of torque vectoring these days that lets the drive system work in conjunction with stability control to help turn-in on corners. The PDCC system in the Panamera incorporates an electronically controlled rear differential. Under cornering forces, the differential can be variably locked, but it can't transfer drive torque to the outside wheel to help push the car around the corner like Acura's SH-AWD system. Instead, the inside rear brake is applied to send torque to the outer wheel.
For really serious drivers, Porsche is also offering the Sports Chrono package that adds a Sport Plus button. In addition to the tighter damping and air springs, this mode drops the whole body by 25 mm.
During the development of the Panamera, the body spent a lot of time in the wind tunnel with several goals in mind. Obviously, aerodynamic drag was one focus, but so was noise reduction. Since this is a luxury high performance car, Porsche wanted the interior to be quiet but still sporting. We were shown one of the wind tunnel clay models used to test various detail design elements. The model had dozens of surface mount microphones embedded in the clay which were used to measure the sound as air flowed over the body.
One of the main sources of audible wind noise in a car at speed is the airflow around the A-pillars and mirrors. The A-pillar of the clay model was easily replaceable and several of the examples were shown, each with a slightly different profile and, hence, a different sound profile. Another aspect of the body that contributed to drag and noise reduction was the underbody, which is completely enclosed on the Panamera. That's a first in this segment, according to Porsche.
The exhaust system engineers also spent plenty of time making sure that sounds that did get through were appropriate for a Porsche. Extensive nodal analysis of both the exhaust flow path and the components within the exhaust system were aimed at producing a deep bark when the car is pushed hard. It was emphasized that no artificial sounds were added to the mix, only the natural sounds of the V8 were allowed through.
Once we finished reviewing all of the Panamera's technology, it was time to go for a "taxi" ride. The Weissach development center has an excellent test track on which to exercise cars that features an array of different kinds of corners, elevation changes and surfaces. Outsiders won't be allowed to drive the Panamera until this summer, though we did have a chance to ride along with some of Porsche's top-notch test drivers. Three of us hopped into a Panamera along with a driver, which instantly highlighted the Panamera's most obvious strength.
Porsches have always been known for having great front seats. Aside from the Cayenne, the back seats in any other Porsche are probably best left simply folded down and forgotten, especially the 911. There is none of that 2+2 nonsense with the Panamera. This is a true four-seater offering rear seats that no one will consider punishment. They're fitting of a sporting car with real lateral support and plenty of space to stretch out. In fact, the 15.7-cu-ft of space under the rear hatch can easily accommodate four suitcases, meaning this could be a real four person road trip machine.
The rear seat backs can fold down 60/40 for those times when you need to pick up some flat pack furniture from IKEA. With both seats folded, the Panamera can accommodate 44.2 cu ft of stuff. For ski weekends, there is also a center pass through preserving both rear seats.
We started off on the track in Comfort mode as our turbo Panamera taxi roared off. Over rough pavement (still much better than typical Michigan roads), the Panamera maintained a remarkably smooth ride for a car with such high performance capability. Tracking through corners, there was some noticeable body roll in this mode. At the end of the first lap, the driver switched over to Sport Plus mode and then did a couple of hot laps.
For a 4,300-pound car with four adult males aboard, the Panamera felt like it was definitely capable of matching Porsche's performance claims of 0-62 mph in just 4.2 seconds. The Sport Plus mode snubbed out roll effectively and kept the body parallel to the ground while still not being too punishing. After a short break, we switched cars and seating positions and got into the back of a normally aspirated 4S.
Those who are susceptible to motion sickness may want to avoid sitting in the back seat of this car with a fast driver. It's not that the car does anything wrong – on the contrary, the capabilities are so high that the weak stomached will experience stronger forces than they are accustomed to. Fortunately, the back seats are up to the task and feel as good as the fronts.
The sensations we felt from the passenger positions of the Panamera definitely had us forgetting what the car's rear profile looks like. It wasn't until we climbed back out that the hunchback returned to mind, and by then it suddenly didn't look so bad. It's still not beautiful, but if we had $100,000 to drop in a quest for a really fast four-seater, this would certainly be on the list. We can't wait to try the Panamera from the driver's seat.
All photos Copyright ©2009 Sam Abuelsamid / Weblogs, Inc.
Our travel and lodging for this media event was provided by the manufacturer.