We drove a 530i on a crystal-clear fall day along fast, two-lane roads tracking the Hudson Valley through upstate New York. And we spent a week in one driving between Washington and Charlottesville, Virginia, and on the winding roads of bucolic Albemarle County.

However, we hadn't even left the parking lot at BMW headquarters in New Jersey when it became apparent that the optional Active Steering system was no gimmick. Maneuvering through tight confines is a breeze. Pulling an empty parking space is as quick a swoop on the steering wheel. Later, 120 miles up the Hudson, we discovered the performance advantages of this new steering system. The 5 Series is quite nimble as heavy sedans go. But on a tight slalom course, we found that a 530i with Active Steering is more responsive than one without it. Weaving through the cones is less work with Active Steering, requiring less sawing at the wheel and fewer corrections. The driver can focus more on the car's trajectory through the course, less on compensating for mistakes. And it's not hard to extrapolate this behavior to advantages in emergency situations on public roads. Push the Active Steering car into a skid, and recovery is more immediate, and more likely.

There's a price for this responsiveness, and it's most obvious traveling at high speeds on an Interstate. Gone is the famous BMW dead spot in the middle of the steering travel, that inch or so of movement each side of center where there is no perceptible change in the 5's direction of travel when the wheel moves. This was developed for decades to account for triple-digits speeds on Germany's autobahns, but it's no longer necessary. With Active Steering, the steering response slows down considerably at fast freeway speeds, but there is perceptible reaction from the front tires almost with the first fraction of movement on the wheel. The effect is basically the same, in that small bumps or grooves require no conscious correction from the driver. But the feel with Active Steering is different. Not everyone likes it, and it may take a bit of getting used to, particularly for longtime BMW enthusiasts. Other drivers really liked it, adapting without even realizing and enjoying the arrowlike precision of the car.

The two-lanes through the Hudson Valley offered ample evidence of the value of Active Roll Stabilization. The 530i stayed remarkably flat when attacking the curves, with just enough body lean to remind a prudent driver that he or she is hurtling down a public road at considerable speed. Perhaps the best thing about ARS is that the 530i never feels stiff. When the car is traveling straight, the effect of the roll stabilization is essentially negated. This sedan rides firm, without a sensation of floating, but always smoothly and comfortably.

Factor in near-perfect weight balance, and a rock-solid body that's free of creaks, rattles or unpleasant vibration, and the 530i is exactly what we'd like a luxury sedan to be: always quiet and comfortable, nimble and reassuring when it's appropriate to travel at a good clip. If you never drove the 5 Series quickly, you'd be left with a smooth, truly comfortable car with nearly all the bells and whistles and nothing to diminish the experience. Yet should you choose to pick up the pace, you'll discover handling and overall performance that's hard to match in any sedan. No matter which engine sits under the hood, there's plenty of power to get you up to speed.

BMW's inline six-cylinder engines remain one of the truly satisfying experiences in motoring. The classic straight six delivers a balance of smoothness, torque, and response that V6 engines can't seem to match. Other luxury manufacturers have switched to V6 engines because they've proven easier to certify for stringent emission standards. We're glad BMW has stuck with its trademark inline engines. From a stop or a high-speed roll, the 530i serves up as much torque as some thirstier V8-powered sedans. BMW reports 0-60 mph times of 6.6 sec. for 530is with manual transmissions, and 6.8 sec with the automatic. Ten years ago, those numbers were the preserve of sports cars, and rest assured that top speed exceeds anything you're likely to get away with anywhere outside desolate Nevada desert. Throttle response is very linear in the 530i. It does not paste you into the back of your seat. Even with the six-speed manual, there's no exciting rush of acceleration. You'll need the V8 for that.

The 525i and 530i six-cylinder engines are relatively unchanged since 2003, though the intake and exhaust systems on both have been fine-tuned to improve low-end response. However, these engines employ leading-edge technologies, including drive-by-wire electronic throttle control and cooling management, fully variable valve timing and all-aluminum construction.

Those who put a premium on straight-line acceleration might want to opt for the V8-powered 545i. The V8 shaves at least a second from the 530i's 0-60 times. Top speed is electronically governed at the voluntary limit adopted by most German automakers: a mere 155 mph. The 4.4-liter V8 has the same displacement as its predecessor, but nearly everything else has changed. Horsepower has increased 12 percent, yet so have fuel efficiency and EPA mileage ratings. The key here is Valvetronic, an industry-first technology introduced on BMW's 7 Series. This engine management system eliminates a conventional throttle and varies engine breathing (and therefore power output) by varying how far the intake valves open.

To enthusiast drivers, we heartily recommend the six-speed manual. Indeed, we appreciate BMW's continued commitment to manual transmissions, as they are becoming rare in luxury sedans. The 530i's shifter is tight and reasonably quick, as you'd expect in a sporting sedan, and clutch take-up is just right. The manual transmission maximizes the performance potential of the 530i, as well as its driver's involvement. We found shifting the manual smooth, precise, easy.

We also tried the automatic, and those who choose it won't give up much. The new six-speed Steptronic automatic responds to the gas pedal in exceptional style. Full-throttle upshifts are quick and smooth; downshifts are almost instantaneous. Not that long ago, BMWs automatics were mediocre compared to the best in the business, but that's no longer the case. Ideally, the automatic would include redundant shift controls on the steering wheel or column, now common in other luxury cars. On the other hand, we were perfectly happy to simply shift into Drive and let it do its job.

BMW's Sequential Manual Gearbox is available on the 530i and 545i. While it will shift automatically, the SMG is not an automatic with a manual shift feature like the Steptronic. It's more like a manual with an automatic clutch. The SMG's clutch operates electrically without input from the driver, who shifts up or down simply by moving the gear lever or clicking paddles on either side of the steering wheel. SMG can also shift automatically, yet it delivers the improved acceleration and fuel mileage of a manual transmission because it eliminates the inefficiencies of a torque converter, called friction losses.

Brakes may be the most impressive part of the 5 Series performance package. They slow the car from high speed in sports-car fashion, and they hold up under harder use than any driver is likely to dish out this side of a race track. Even after repeated full-on stops, stops that would smoke the brake pads on lesser cars, the 530i's brakes show very little fade. BMW's brakes are large by industry standards, and all discs are vented to maximize cooling.

Yet the hottest technologies in the 5 Series suspension are difficult to see, even by crawling under the car. Active Roll Stabilization replaces conventional anti-roll bars with an electronically controlled, hydraulically operated system. The system helps keep the body from leaning over in corners, allowing flatter cornering at higher speeds while maintaining a nice smooth ride quality.

The Adaptive xenon headlights are excellent with sharp cutoff and even lighting. We found them to be real benefit on winding rural roads at night. The 5 Series is not whisper quiet like the 7 Series; wind noise and tire whir enter the cabin.

The 5 Series feels smaller on the road than its dimensions suggest. This latest generation of the 5 Series is 2.6 inches longer, 1.8 inches wider and 1.3 inches taller than the previous version, and its wheelbase has increased 2.6 inches. Extensive use of aluminum keeps a lid on weight, however. Depending on equipment, some models are up to 55 pounds lighter than their predecessors. A new aluminum driveshaft saves 13 pounds compared to the previous steel part. The hood, front fenders and frame in front of the windshield pillars are also aluminum, glued and riveted to the rest of the car to avoid the corrosion typical of aluminum-steel contact points. The lighter front clip also helps in BMW's never-ending quest for perfect weight distribution, and all three 5 Series sedans are within 1 percent of the ideal 50/50 balance, front to rear. Aluminum suspension components mean less unsprung weight for better tire contact on bumpy road surfaces. The light weight, rigid chassis and arrow-like precision all contribute to this feeling of compactness on the road. It makes the 5 Series cars a joy to drive at high speeds.