The 9-5 Arc leans in corners, a traditional Saab trait that improves handling on bumpy pavement and gravel roads. At the same time, the Arc offers good grip in smooth, paved corners. Steering was a bit slow, again, a Saab trait, but precise.

The Aero, meanwhile, feels firm over light bumps. The chassis jounces up and down noticeably. It's not sharp, nor uncomfortable, but if you peek out the corners of your eyes to the edges of the windshield, you can see the bouncing. The steering remains very steady through this, nonetheless.

Torque steer, that tugging sensation on the steering wheel when accelerating hard in a powerful front-wheel-drive car, is minimal in the 9-5, even in the 250-horsepower Aero, but you will notice it when you nail the accelerator. We also noticed a slight amount of road vibration coming through the Aero's steering wheel at low speeds, but this allows the driver to better read changing road surfaces. The Michelin Pilot tires on the 9-5 Aero are superb: quiet, responsive for handling and threshold braking, yet reasonably capable for all-season driving.

The 9-5 is very quiet on the freeway. We noticed only the slightest hiss of wind noise, and that was eliminated when we closed the interior panel under the sunroof.

The Aero offers quick, responsive performance with its 250-horsepower turbocharged engine. It can generate impressive acceleration from a standing start, but it's best appreciated on the open highway. Squeeze down on the throttle while cruising at 70 mph and you are instantly past that string of cars, a great feature when trying to pass on a two-lane highway. It's easy to modulate the throttle, to get just as much thrust as you need. Squeeze gently on the gas and more power sends the car smoothly ahead. Push down harder and you're suddenly going very fast.

The five-speed automatic transmission is very responsive, downshifting smoothly to the appropriate gear without wasting time. Five gears keep the engine revving in the ideal power band for better response. In Normal mode, this transmission works like a standard automatic. Manual mode activates the Sensotronic manual-shifting feature, allowing the driver to change gears by pressing a pair of buttons on the steering wheel. There's also a Sport mode that shifts automatically with sportier response, and a Winter mode that locks our first gear for more for stable traction in icy conditions. We prefer the Normal mode, letting the responsive automatic do its thing.

The manual transmission shift smoothly, especially between third and fourth gears. For enthusiast drivers, heel-and-toe downshifting is relatively easy. Saabs with manual transmissions have to be shifted into reverse before you can pull the key from the ignition.

The Electronic Stability Program (ESP) helps drivers maintain control by selectively applying the brakes to individual wheels to correct a skid. If the driver goes into a corner too fast for the conditions the system can correct for oversteer (when the rear tires lose grip) by automatically applying the brakes to the outer wheels to bring the car back into line. This occurs automatically; the driver doesn't need to do anything but continue to steer the car along his or her intended path. The system also works when a slippery road causes the car to understeer (when the nose of the car refuses to turn in). Saab worked closely with Bosch, the German company that supplies the system, to achieve optimum tuning. Saab tested the system extensively in the slippery Scandinavian Arctic and at very high speeds at the Hockenheim racing circuit in Germany. Saab claims its stability program is one of the best in the world, and we can't argue.

As mentioned, the 9-5 is equipped with anti-lock brakes (ABS), electronic brake-force distribution (EBD), and an electronic traction control system (TCS). ESP works with the rest of this alphabet soup, helping the driver to maintain control in all sorts of conditions. It allows the driver to maintain steering control when jamming on the brakes, while stopping the car in the shortest possible distance. Several repeated ABS stops from 70 mph showed that the brakes are extremely effective, bringing both the Aero and the Arc to a rapid, uneventful halt with no apparent fade. Whether used for a panic-stop or high-performance applications, the Saab 9-5's brakes are up to the task.

The optional bi-xenon lights are a big improvement over the standard composite halogen lights, though the high beams seem to flare a bit.