Standard features for the Premium Plus trim include 18-inch wheels with summer performance tires, automatic LED headlights, automatic wipers, power-folding mirrors with heating, a panoramic sunroof, front and rear parking sensors, keyless entry and ignition, tri-zone automatic climate control, leather and simulated suede upholstery, power front seats (with heating and massage functions), driver-seat memory settings, 40/20/40-split folding rear seats, auto-dimming mirrors and interior ambient lighting.

On the technology front, you also get Bluetooth, a 7-inch infotainment display, a rearview camera, a Wi-Fi hotspot, remote control via a smartphone app, Apple CarPlay and Android Auto smartphone integration, and a 19-speaker Bang & Olufsen premium surround-sound audio system with a CD player, satellite and HD radio, two USB ports and dual SD card slots. Additional safety features include low-speed forward collision warning and mitigation, blind-spot monitoring with rear cross-traffic alert, and Audi Connect Care emergency telematics.

The Prestige trim includes all of the above, along with a virtual instrument panel display, streaming internet radio apps, remote vehicle monitoring via a smartphone app, a bigger 8.3-inch infotainment display, a navigation system, a tracepad feature for infotainment input and a top-down parking camera system. All of these items are available as options on the Premium Plus trim.

Other options include the S Sport package (red brake calipers, adaptive suspension dampers and sport rear differential); the Warm Weather package (ventilated front seats and extended premium leather upholstery); an adaptive steering system; and a heated steering wheel. The Prestige trim is eligible for the Driver Assistance package that adds traffic-adaptive cruise control, a traffic sign reader, lane departure warning and intervention, and automatic high beams.

From a standstill, the S4 responds a little leisurely. But keep your foot in it and a moment later the S4 is accelerating fiercely. In our testing, which utilized the S4's launch control, the S4 blasted to 60 mph in just 4.3 seconds. That's plenty of power for everyday driving.

The pedal is firm but easy to modulate in normal driving, and you'll have confidence in the brakes for enthusiastic driving as well. There's sports-car-worthy performance here, with stops from 60 mph in just 105 feet. But track testing revealed a noisy ABS and brake fade after multiple panic stops.

There are variable steering efforts available. All are accurate and well matched to their respective setting. Feedback can be lacking, even under spirited driving, but when pushed to the limit, the S4 communicates the available front grip quite well.

The S4's sport rear differential, part of the S Sport package, enhances the S4 enthusiastic turn-in. Even sports cars would have a hard time matching the S4's pace on a tight, twisty road. Longer sweepers, however, tax the Audi's front tires to the point of moderate understeer.

While the eight-speed automatic can be a little too eager to upshift in Drive, you can easily fix that by selecting the Sport mode. The stout V6 and adjustable drive modes allow the Audi to be adaptable to all conditions.

The S Sport front seats are wonderful examples of very supportive yet nonintrusive seating. The front seats offer heating but not ventilation. The rear seats are more than adequately comfortable for a sedan of this size, allowing adults to be comfortable on longer trips.

The optional Sport Adaptive Damping is the way to go on the S4. Comfort mode handles rough and broken road surfaces with aplomb, while Dynamic mode keeps the body in check even under the most spirited driving.

The S4 is relatively silent at all speeds, well isolated from both road and wind noise. Only under hard acceleration does the engine's pleasing V6 snarl become prominent. Tire noise is minimal, which is a pleasant surprise for summer-rated tires.

Clear, self-explanatory and easy to use, the S4's three-zone climate interface sets an example for the class. The pressure-sensitive buttons seem like unnecessary flair, but they still work without delay. It's refreshing to see climate control not buried in an on-screen menu.

It's hard to argue with an Audi interior — controls are clear, logically arranged and consistent in both look and feel. The configurable instrument panel does take some time to learn, but it presents a wide array of information. Audi's MMI becomes intuitive after only a few uses.

Even with the wonderfully supportive sport seats, the S4 is as easy to get in and out of as any other small luxury sedan. Taller rear-seat occupants might have to duck their head to clear the roofline, but there is ample door opening for a graceful entry and exit.

With the combination of the sport front seats and the S4's exceptionally ergonomic and highly adjustable steering wheel, drivers of all sizes will be able to find a suitable position within a few seconds. Driver fatigue is unlikely to ever be an issue. Definitely a benchmark.

Front-seat occupants have ample head-, leg- and shoulder room. While taller rear-seat passengers might find it a tight fit behind a taller driver, two passengers would be comfortable for moderate distances, which is on par for not only the class but for most midsize sedans.

Bucking the trend of high beltlines and even higher trunks, the S4 is an example of a modern sedan that offers good visibility. Blind spots are minimal.

All-around build quality is excellent and on par with what we've come to expect from Audi. There are no unsightly connections, welds or hinges. The brushed aluminum interior trim does look and feel plasticky, but that's the only letdown.

Storage isn't abundant, but there's enough room to keep your phone, sunglasses, parking card and drinks free and clear of your hands while driving.

Though the trunk isn't overly large, the load height is reasonable, and the cargo area is free of any intrusions or irregularities.

Easily accessible LATCH anchors are available for the rear seats and the normal size door opening makes access less of an inconvenience.

The Bang & Olufsen audio system is excellent, capable of handling a wide variety of music and volume with exceptional clarity. Navigation utilizes Google Earth and is viewable on the center-mounted display as well as in the S4's Virtual Cockpit.

Both Apple CarPlay and Android Auto are available, but the native Audi systems are so good that all of our drivers preferred not to use their phones for anything other than Bluetooth audio.

Along with a not-too-intrusive and easily defeatable stability control, Audi also offers its Pre Sense predictive system that offers maximum braking performance when an accident is anticipated. Rear and side assists, blind-spot monitoring and adaptive cruise control are available at extra cost.