A major Asian carmaker recently abandoned a 12-year-old platform heritage featuring parts interchangeability that was arguably responsible for the growth of an industry. It was imitated in its most important features by makers of vastly more expensive cars, but then the company changed everything, to the very heart of the chassis' concept. Still, people who drive the new cars say the most remarkable thing about them is how they feel exactly like the old cars.

In contrast, Saab has thoroughly revised its 9-5 Sedan and Wagon, making 1,265 changes, but only to parts that mattered. The result is a car deceptively similar to those sold since 1997 but one that feels entirely different and entirely better. Indeed, some observers may have to park the new cars next to those they replace in order to see the differences. From the inside, though, it's apparent the engineers and stylists were earning their kronor. When driving the new 9-5 it gets even better, with a more powerful Aero and what must be the best chassis dynamics in any factory Saab, ever.

The big news for engines available in the U.S. will be the 2.3L High Output Turbo that powers the high-performance Aero models. It now will produce 250 bhp, an increase of 20 bhp. One of Saab's powertrain engineers present told me that, although this engine's throttle, turbo boost pressure and bypass valve are all controlled by Saab's own Trionic management system, the increase was achieved through improved fuel and spark mapping only, without raising boost pressure. Peak torque stays at 242 lb-ft from 1900-4000 rpm, with 256 lb-ft available for up to 20 sec. at a time.

Vehicles equipped with an automatic transmission benefit doubly. A new five-speed box, which will be available throughout the 9-5 range, can handle the full 242 lb-ft, whereas past 9-5 Aeros equipped with the four-speed it replaces were restricted to 228 lb-ft. Saab states the five-speed automatic doesn't just allow more torque, it provides a smoother, more responsive drive by keeping the HOT engine in its mid-range "sweet spot."

Saab's 185-bhp 2.3L turbo and 200-bhp 3.0L asymmetrically turbocharged V6 remain unchanged. In the latter, the turbine is driven by the exhaust gases of only one cylinder bank, while the compressor feeds all cylinders. This technique is a production first, but Garrett, which makes every turbo Saab uses, has been doing it for some time in CART.

Saab's new V6 TiD 3.0L is a major step for Saab in the European market, where roughly 40 percent of passenger cars are powered by diesel, but it won't be available in the U.S. Though basic work was done in Japan by Isuzu, another GM partner, Saab's requirements were considered from the beginning, and the final airflow and management were engineered by Saab. The TiD is a true Saab engine, underlined by the fact that Saab is the first company to sell a version to the public.

The TiD uses common-rail injection and a Garrett Variable-Nozzle Turbine, which provides rapid response, a broader performance envelope and eliminates the need for a wastegate. Torque is 242 lb-ft from 1800 to 3000 rpm, with 176 bhp at 4000 rpm. I drove a 9-5 with the V6 TiD and found it quite satisfactory. It's smooth and quiet at cruise, torquey and responsive around town. Only at speeds below 1000 rpm, such as when engaging the clutch from rest, did it sound at all like a Dodge Cummins. Despite benefiting from an aluminum block and all the latest technology, the V6 TiD is heavier than Saab's other powerplants simply because it is a diesel.

Though the V6 TiD will not be available in the U.S., it required changes to the 9-5 chassis that will be very much appreciated by U.S. customers. Several chassis components have been made lighter and stiffer as well as having improved geometry. Steering knuckles are now made from aluminum and have longer steering arms. Thus, the steering ratio is slowed somewhat, but the power steering has been retuned to compensate, enhancing steering feel versus the old models. The front subframe has been lightened and stiffened, and upper strut mountings are stronger, improving longitudinal rigidity and lateral response. At the rear, trailing-arm bushings were stiffened for better control.

With a rigid chassis to support them, the springs and anti-roll bars were stiffened and dampers improved. The latter were not merely adjusted for the stiffer springs, they were tuned with a completely different concept. Driving the cars, one can feel there is proportionally more compression damping than before, giving a sportier, more responsive BMW-like feel at the same time that ride comfort is improved. The Aero is still stiffer and 10mm lower than the less sporting models. Saab credits new Michelin tires with improving stability and steering response, whether on-center, turn-in or in the corner. Electronic Stability Program will be available for the first time on a Saab, but it's difficult for me to comment on it. Testing was limited to an unused runway on which cones were arranged, as my driving partner said, "to cause you to do something stupid with the car so you could feel the ESP work." Benchmarks in chassis testing cited by Saab include the Audi A6, BMW 5 Series, Mercedes-Benz E-Class and Volvo S80. Suffice it to say the new 9-5 is very, very good, and still a Saab.

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