IMPORTANT NEWS: National Electric Vehicle Sweden has agreed to buy the assets of Saab Automobile and the sale is expected to be finalized during the summer.

Sunday, March 27, 2011

Auto Motor & Sport on upcoming 9-3 design and architecture

Swedish car magazine Auto Motor & Sport had a talk with Jason Castriota at the Geneva Motor Show. The interview and report from Geneva is available in issue number 6. Here are some of the information they got out of the Saab people in Geneva.

Low drag
Jason Castriota tells Auto Motor & Sport that he has gotten the drag coefficient of the next Saab 9-3 down to just 0.26. And as far as I can tell, that is actually very good. The current 9-3 SportSedan and the new 9-5 Sedan have drag coefficients of 0.28, which is also good, but not outstanding.

So why is a low drag coefficient so important? Well, because lower drag means lower fuel consumption and thus lower emissions. In todays market low consumption and low emissions are very important, especially in Europe where many countries tax emissions. The big challenge is to reduce drag and at the same time have enough downforce to give the car aerodynamic stability and great cornering ability.

The lowest drag coefficient I know of in normal production cars is 0.25, e.g. the Honda Insight and the Toyota Prius, but to me it seems like the Japanese had more focus on drag than beautiful design and impressive driving characteristics…

One car that has both a beautiful design and a low drag, and I assume great driving characteristics, is the new Mercedes-Benz CLS with a drag of just 0.26, the same Castriota says he has achieved with the new 9-3.

In addition to drag, size of the frontal area is also important, but on this we get no information about the new 9-3.

A side note about importance of drag
German car magazine AutoBild did a test a few years back (2008-04-11 issue) where they tested several cars in a wind tunnel. Their conclusions are very interesting:
  • Already at 50 to 80 km/h (depending on the car), aerodynamic drag becomes the most important factor for lower fuel consumption.
  • When comparing drag and weight by measuring by fuel consumption, reducing the Cd from 0.29 to 0.28 is like eliminating 100 kg vehicle weight

The design of the next 9-3
To AMS, Castriota says that the style of the upcoming 9-3 will not be as extreme as the PhoeniX concept. Instead it will be a mix of the balanced and beautiful lines of the Aero-X and the extreme shapes of the PhoeniX. Big parts of the front design of the PhoeniX are close to the 9-3 design. The most noticeable difference is the headlights which will be bigger on the 9-3. The body painted wing across the grille and into the head lights will follow over to the 9-3, as will the nicely shaped bonnet. The next 9-3 will get bigger and more prominent front wheel arches, and will also get a wraparound windshield. The hatchback will get an even flatter roof line and lower rear end than the PhoeniX concept.

About the architecture
Auto Motor & Sport tells us that Jan Åke Jonsson, when Saab was headed into a divorce from GM in 2008, wanted Saab to create their own basic vehicle structure. Technical director, Mats Fägerhag, then starting to plan a solution based on the Scania platform approach: One basic architecture shared by both the 9-3 and the 9-5, as well as the 9-4X. The name Phoenix was suggested by Kjell ac Bergström.

One advantage of the new platform compared to GM's delta platform, which the 9-3 was supposed to be built on under GM, is that the chassis and drive line is more than 100 kg lighter than GM-solution. Saab has also worked much on reducing the front overhang and thus moving the front wheels forward. This gives better driving characteristics and a more flexible engine bay which is suitable for different engine suppliers.

Doesn't a drag coefficient of just 0.26, lighter architecture and a design mix of the Aero-X and the PhoeniX sound exciting? I think so!