Saab 9-3: Design & Aerodynamics

Distinctive Sport Sedan Styling

• Sporty, coupé-like exterior styling
• Wider body, longer wheelbase gives more spacious cabin
• Distinctive Saab design harmonizes exterior and interior
• Excellent high speed stability, low lift forces, low 0.28 Cd.

“Saab’s design DNA runs right through this car. It looks clean, modern and sporty, combining some traditional Saab styling cues inside and out with the best timeless qualities of Scandinavian design.”
– Michael Mauer, Executive Director, Design

The styling of the new 9-3 clearly positions it as a sport sedan from Saab. The harmonious lines are soft and organic, yet well defined, communicating the car’s sporty character through an impression of power and strength.

The gently arching roofline flows between the steeply raked front and rear windows to create a coupé-like profile. Within this format, the design team has stamped out the car’s distinctive Saab personality by combining sweeping lines and harmonious curves for both the exterior and interior.

Exterior design
Compared to its predecessor, the new car is 2.1 inches wider and benefits from a 2.8-in. longer wheelbase. The shorter front and rear overhangs mean the overall length of the car is similar at 182.5 inches. The more purposeful stance is also reinforced by a small .4-in. (10mm) reduction in ride height.

The swept back, frontal styling clearly establishes the new 9-3’s sporty credentials. The “delta” effect of the Saab grille with its integrated headlamp units steeply angled back is a striking evolution, the rearmost corner of each housing being swept back 17.7 inches behind the center point of the bumper. It is a similar angle to the delta wing in the Saab grille and also matches the traditional wraparound proportions of the windshield.

The finely-proportioned profile of the car also incorporates widely-recognized Saab styling cues: the combined teardrop form of the side windows with a disguised B-pillar; the wedge shape and high waistline culminating in that distinctive “hockey stick” curve into the C-pillar; a single swage line running the entire length of the car and, of course, the oval-shaped door handles.

The new 9-3 becomes the first Saab to incorporate a “monoside” body pressing, the inset mounting of the doors allowing extremely fine shut-line tolerances, giving the car a strong rock-solid appearance, as well as further improving aerodynamic efficiency.

On most variants, the lower ride height is emphasized by the deep, color-keyed side sills and front and rear bumper moldings, making the whole body appear low-slung and close to the ground. The curvature of the wheel arches, with reduced clearances, and the location of the wheels (15-, 16-, or 17-inch) close to the outer edges of the bodywork with negative camber contributes to a more purposeful stance. The new 9-3 Vector’s sporty styling is taken one step further with discreet side sill flares and bumper extensions.

At the rear, the triangular, side cut-out of the light clusters is another Saab design signature, as is the subtle, raised rear lip of the trunk lid first seen on the Saab 9-5 sedan. The rear proportions of car are particularly clean and well-balanced, the horizontal sweep of the rear light clusters providing a counterpoint to the vertical lines of the tail. Apart from a Saab emblem on the hood, the trunk lid carries the car’s only other visible badging: the 9-3 model designation on the left and the engine denomination on the right, flanking the Saab badge.

“The car’s shape is intended to reflect its essential character, which is dynamic and sporty. It also avoids any ‘faddish’ styling, which is not the Saab way and dates very quickly,” explains Aamer Mahmud, Chief Designer, Saab 9-3.

“The coupé-like profile, the teardrop shape of the side windows, the shorter front and rear overhangs and the way the wheels fill out the wheel-arches are all features intended to make this car look like it is moving even when it is standing still,” he added.

Interior design
The artistically sculptured interior of the new Saab 9-3 provides spacious and comfortable accommodation for four adults. It is larger in a number of key dimensions than that of its predecessor. The use of high-quality materials and the standard of fit and finish is everything you would expect – and more – from a premium-class manufacturer such as Saab.

The generous shoulder width is 3.2-in. wider in the front and 2.6-in. wider for rear passengers. The longer wheelbase means that rear passengers also enjoy a useful 1.5-in. increase in legroom.

The overall design echoes the soft curves and flowing lines of the exterior. In the same way, its unfussy styling is clearly a natural evolution from previous Saab models. The dash fascia layout, the supportive seating, the shape of the door panels and the feel of the tactile, soft-touch controls are all very modern interpretations of classic Saab styling themes. It is a harmonious interior that could only come from Saab.

Attention to detail, so typical of Saab, is everywhere to be seen. The gentle contours in the B-pillar trim are a precise continuation of the lines in the door panels. The rear seat belts are neatly housed just above the rear seatbacks, avoiding unsightly slots in the C-pillars. The LED for the alarm is integrated into the dash-top sun sensor. Even the seat height adjustment levers are coated in a soft-touch plastic finish.

The interior is presented in a choice of parchment or gray tones and three interior specification levels or “Forms”: Linear, Arc and Vector (see Interior Features section for details).

Aerodynamics
The final shape of the new Saab 9-3 is the product of a close liaison between body stylists and aerodynamicists. Saab’s decision to move from a hatchback shape with a relatively narrow track to a wider sedan format posed a tough challenge to the ingenuity of Chief Aerodynamicist Hakan Danielson and his team. Their mission was to produce a shape that slices through the air as efficiently as possible, giving good high-speed stability, optimized fuel consumption and low wind noise inside the car. The result is an impressive drag coefficient of 0.28, equaling best-in-class performance.

“We have managed to reduce the Cd value by more than 10 percent compared to the old model, even though the increased width of this car means we are punching a bigger hole in the air,” says Danielson.

Slippery shape
The team concentrated their efforts on achieving a smooth airflow over, around, through and under the car, paying particular attention to points of flow separation at the rear in order to reduce turbulence, by reducing the size of the car’s wake, and improve stability. The shaping of the side sills and the radius and curvature of the rear corner of the C-pillar also helps reduce drag.

The rear edge of the hood rises to smooth the passage of air over and around the windshield. The team also worked hard to reduce disturbance where the bottom of the rear window joins the trunk deck, a particularly sensitive area in notchback shapes. The subtle upturn of the rear edge of the trunk lid is, in effect, an integral lip spoiler that helps reduce the size of the car’s wake, the area of turbulent air that trails behind the car at speed.

Good airflow management also contributes to keeping the windows of the car as free from road grime as possible. For example, the door mirror casings have a small spoiler-like profile in the bottom surface to reduce contamination of the side windows.

In addition to its excellent low drag shape, the team has made major strides in improving stability. Compared to its predecessor, lift forces at the rear axle – an important determinant of high speed stability, especially under braking – are reduced by an impressive 30 percent. A value of 0.11 Clr (coefficient of rear lift) is again on a par with best in class.

Low wind noise
Special attention has been given to reducing wind noise. The adoption of monoside body pressings, with inset doors and seals, makes a significant contribution. There has also been fine tuning of the A-pillars and door mirrors.

The traditionally deep curvature of the windshield reduces the acceleration of the airflow as it approaches the A-pillars, which have a flattened radius where they connect to the windshield to minimize airflow disturbance. The bottom edge of the door mirror casings is also extended rearwards by .2 inches (5 mm) to further reduce the likelihood of wind noise at speed.

Good airflow management even plays a safety role in the new 9-3. The wraparound rear light clusters have an optimized radius that gives a distinct separation for airflow along the side of the car. However, careful shaping of the angle actually helps the air “turn the corner” first before it separates. The creation of a flow over part of the light clusters has the effect of helping to reduce the build up of road grime, which can impair the visibility of the lights.

Under the car
Airflow underneath the car is becoming an increasingly important area for fine tuning. The forward lower link of the rear suspension has been aerodynamically shaped to reduce wind resistance and minimize the accumulation of road grime on the wheel rims. It is the first time Saab has aerodynamically shaped a suspension part.

Shielding of the ventilated air from the cabin reduces disturbance where it exits behind the rear wheel housing. Airflow under the hood, within the engine bay and at the bottom of the front footwells was also closely scrutinized.

Testing
Advanced CFD (Computational Fluid Dynamics) modeling now replaces a great deal of laborious work in the wind tunnel and also allows faster, more effective communication between project team members. For example, CFD played a vital role in the visualization of airflow and speeded up fine tuning in the wind tunnel.

CFD was also the main tool for optimizing internal airflows: in the engine bay to control heat build-up from the engine and in the passenger compartment for best possible comfort.

Full-scale optimization work was carried out in the wind tunnel at Stuttgart University, using a rolling road. But before that work began, advanced test methods developed by Saab made it possible to test up to 70 different body shapes in one-fifth scale during an eight-hour shift in the tunnel. In this way, aerodynamicists and designers work very closely together and a large number of suggested changes can be investigated to meet aerodynamic targets.

Further wind tunnel testing was also carried out at the Motor Industry Research Association (MIRA) in the United Kingdom and in Detroit, for wind-noise suppression.

New Saab 9-3 In Focus: Handling the Handshake
First impressions are always important. A firm handshake, for example, inspires confidence and that’s what the door handles of the new Saab 9-3 are designed to do. “It’s like meeting someone for the first time,” explains Aamer Mahmud, Chief Designer, Saab 9-3. “The door handle is the first contact a customer has with the car and it should make the right impression.” For Saab that means having a very robust, strong and easy-to-use design. Saab’s signature oval door handles can be gripped easily from the top or bottom, whichever is most comfortable. Women do not risk damaging fingernails, and gloves do not need to be removed. And in the unlikely event of a door being jammed shut in an emergency, a rope or chain can be easily looped around the handle.

“The handles are robust and honest in the Scandinavian way, where form should follow function,” adds Mahmud.

New Saab 9-3 In Focus – Unique Front Wheel Spoiler
“From my point of view, it would be great if the new car was about a foot narrower and six feet longer,” jokes Hakan Danielson. “However, we are designing a road car, not a land-speed-record breaker!”

Behind the jocularity, Danielson makes the point that he can never achieve aerodynamic perfection in the real world. Instead, his team must concentrate their efforts where the return is greatest. As a result, they have developed a unique “two-step” spoiler ahead of the new Saab 9-3’s front wheels. Although subtle, the carefully shaped molding makes a significant contribution to the smoothing the passage of air under the car.

“We have put a lot of work into this area,” says Danielson. “There is a great deal of turbulence around the front wheels and inside the wheel arches. This disrupts the smooth flow of air under the car, so we have carefully shaped the spoiler to lead the air away from these areas, channeling it exactly where we want it to go.

“No one has put as much effort into this feature as we have at Saab, and we are convinced it has been worthwhile. The results in the wind tunnel prove how effective it is.”