In the 2009 Audi A4 -- due in dealerships in September -- the car's debt to more expensive siblings is obvious, from the robot-reptile stare of its LED headlights (first seen on the R8) to the tensed ligature of its styling and the sheer affront of its, well, front. The car is, and looks like, a four-door version of the new A5 coupe. But the car also features several systems that are virtually brand new, including the trick Audi Drive Select -- a system to incrementally sharpen the car's sporting responses (steering, transmission shift points, suspension stiffness). Other hot-off-the-workbench technologies: dynamic steering (providing small degrees of counter-steering correction as the car reaches the limits of handling); lane-departure warning; side-object warning system; automated cruise control.

Taken on its own, none of these systems are revolutionary, or even first to market. Put them all together and stuff them into a midsize German sedan that, fully optioned, costs less than $40,000 -- and make that sedan a model of holistic cool, utterly balanced, deeply charismatic, somehow inevitable -- and you have a car that can launch a second renaissance of Audi. And considering Audi spent $1 billion on what's called the B8 program, that's probably what it had in mind.

But first, the tale of the tape. Compared with the previous generation A4, the new car is 4.6 inches longer, 2.1 inches wider, over a wheelbase massively stretched by 6.5 inches. Like the A5, the A4's powertrain has been designed so that the front differential is situated between the engine and transmission, allowing the front-wheel centerline to be pushed toward the front of the car.

A bunch of good things happen as a consequence: One, the layout creates more cabin space (room in the foot wells) without adding a lot of size and mass (the car weighs a mere 88 pounds more than the previous A4); two, the shorter overhang gives the car a more athletic and aesthetic stance; three, less weight ahead of the wheels improves handling, because it reduces the mass in the pendulum, so to speak; four, a longer wheelbase means a smoother ride. It's all good.

So the new A4 is bigger, and it feels bigger still on account of the packaging (the sedan has a huge 17-cubic-foot trunk, and the Avant wagon has a maximum cargo space of 50 cubic feet, bigger than a lot of midsize SUVs). In the previous A4, rear-cabin accommodations were strictly steerage. In the new car, the rear passengers can actually un-kink a little.

The U.S. versions of the car will come with either a 2.0-liter turbocharged four cylinder (211 hp) or a naturally aspirated 3.2-liter V6 (265 hp), both high-tech, direct-injection engines with variable-valve timing. I tested the 3.2-liter with a six-speed Tiptronic transmission and the Quattro all-wheel drive system (standard on the V6 models and optional on the 2.0-liter cars). A year ago, the V6 powertrain would have been the hot setup. This year, I suspect a lot of shoppers will be interested in the torquey and limber turbocharged 2.0-liter (258 pound-feet between 1,500 to 4,200 rpm), paired with a new continuously variable transmission (front-wheel-drive version only). The CVT includes a sport mode that simulates an eight-speed transmission with paddle shifters. I estimate highway fuel economy in excess of 30 miles per gallon, and Audi reckons the 2.0-liter with the CVT will dash to 60 mph in 7.1 seconds.

The Audi Drive Select works a lot like the Manetto in the Ferrari F430, ratcheting up the algorithms that control throttle response, variable-rate steering, transmission behavior (gear-holding and shift points) and the adjustable-rate suspension, from comfort to sport (there's also a personal setting if you really want to fiddle with the thing). The big news here is that the system actually makes a difference in the handling of the car. In some cars -- the Porsche 911, for instance -- the adjustable suspension buttons don't seem to be connected to anything. The effect is too subtle for most buyers to appreciate. Driving a Southern California freeway, with the system on comfort, the A4 (with the optional 18-inch wheels and summer tires) practically floats, recovering from road imperfections in buoyant gentle swells. In these conditions the car's Megapascal stiffness and decibel damping make it feel like a seriously large and expensive car. Put the system on sport, however, and the ride gets hard and leathery. Get thee to a snaky country road, and quick. The lesson here is this: If your driving habits take you to only one kind of road -- soul-killing freeway commutes, for instance -- you can probably save your money.

To me, the A4 is an interesting looking car, with more of a connoisseur's story to tell; still, if you're comparing it with the class of the field, you'd have to conclude that the BMW 3-series cars -- sedans and coupes -- are a little quicker and offer a little better fuel economy. Also, the BMW's ride and handling compromise cannot be beat, no matter how many semiconductors you throw against it. The A4, on the other hand, is less expensive and generally richer in textures and features. The glossy wood, creamy leather and bright alloy piping in the cabin would make the local yacht club commodore give up the sea.

From the optional 14-speaker Bang & Olufsen sound system to the standard MMI multifunction interface (think iDrive without the suicide watch), the A4 feels like an A8 luxury cruiser that has fallen into a shrinking ray.

It's not like the franchise was in danger, but the A4 saves it anyway.