The 2015 Audi S5 exemplifies the appeal of sport-luxury coupes and convertibles. It offers blistering performance, of course -- but in this segment, that's just the beginning. When you're simply commuting on surface streets or eating up miles on the highway, the S5 is at your beck and call with a supple, quiet ride and an interior that's exceptionally refined and accommodating. Then there's the styling, which continues to rank among the sexiest in this class. The S5 is a car that does it all, and that's why discerning shoppers are willing to meet its substantial price.

Splitting the difference between the merely excellent A5 and the extraordinary RS 5 (both reviewed separately), the 'tweener S5 may be the sweet spot in this trio. Its supercharged V6 serves up a tantalizing 333 horsepower, eclipsing the A5's four-cylinder engine by more than 100 horses while keeping a respectful distance from the RS 5's 450-hp V8. If you're the type who prefers three pedals, the S5 coupe also offers a six-speed manual transmission that's unavailable on the RS 5. And if you're thinking about fuel economy, the S5 gets up to 28 mpg highway, trouncing the RS 5 by a whopping 10 mpg and even approaching the A5's 32 mpg peak.

If there's a strike against the S5, it's the simple fact that there many compelling ways to spend this kind of money. You could go with the 2015 BMW 435i coupe or hardtop convertible, for example, each packing 300 overachieving ponies of its own. The 2015 Mercedes-Benz C350 coupe offers comparable power to the BMW, and these German alternatives are also available with all-wheel drive. If you don't mind spending a bit more, the stately 2015 Mercedes-Benz E550 coupe and cabriolet serve up a buttery twin-turbo V8. On the home front, the value-packed 2015 Ford Mustang GT intrigues with its classed-up interior and authoritative V8 power, and if you don't need the backseat, the 2015 Chevrolet Corvette beckons with world-beating performance and newfound sophistication for S5 money.

But maybe none of these alternatives catches your attention like the four rings adorning the 2015 Audi S5's grille. An unusually civilized blend of style, swiftness and comfort continues to set this Audi apart -- which is why it earned an Edmunds "A" rating from our testing team.

The 2015 Audi S5 is offered in coupe and convertible (cabriolet) body styles. The latter features a power-operated soft top and a wind blocker. Both are available in Premium Plus and Prestige trim levels.

Standard Premium Plus features include 18-inch wheels shod with summer tires, xenon headlights, LED running lights and taillights, heated and auto-dimming mirrors, an S5-specific body kit, a tilt-only sunroof, and keyless entry and ignition. On the inside the S5 Premium Plus features tri-zone automatic climate control, brushed aluminum trim, leather and simulated suede upholstery (coupe) or upgraded leather upholstery (convertible), heated eight-way power front sport seats (with four-way driver power lumbar), driver memory functions, an auto-dimming rearview mirror, a color driver information center, split-folding rear seatbacks, Bluetooth phone connectivity, a dash-mounted MMI electronics controller, a 6.5-inch display, the Audi Drive Select system (providing driver control over steering, throttle and automatic transmission calibrations), shift paddles for the automatic transmission and a 10-speaker sound system with a CD player, satellite radio and iPod integration.

The Prestige adds adaptive headlights, a Bang & Olufsen sound system (with 14 speakers for the coupe and 12 for the convertible; optional on Premium Plus) and the Technology package. The latter includes Bluetooth streaming audio, Audi Connect with online services and mobile WiFi, a navigation system, a 7-inch display, an upgraded MMI interface with console-mounted controls, HD radio, front and rear parking sensors, a rearview camera and a blind-spot monitor.

The Premium Plus trim can be equipped with the Technology package as an option, and both coupe trims are also eligible for the upgraded leather upholstery. The convertible trims already come with the fancy leather, but they're eligible for a Comfort package that features different leather upholstery and special front seats with a neck-level heating system, less aggressive side bolsters and power lumbar for both driver and passenger. Only the Prestige models are eligible for the Driver Assist package that adds adaptive steering and adaptive cruise control with a forward collision mitigation system.

Stand-alone options include assorted 19-inch wheels, a torque-vectoring sport differential, an adaptive suspension, various interior trim accents and a coupe-only High Gloss Black package that adds special 19-inch wheels, a blacked-out grille, body-color exterior mirrors and gloss-black window surrounds.

The 2015 Audi S5 is motivated by a supercharged 3.0-liter V6 engine rated at 333 hp and 325 pound-feet of torque. The coupe comes standard with a six-speed manual transmission, while the cabriolet gets a seven-speed automated manual transmission that's optional on the coupe. Every S5 features all-wheel drive, optionally with a sport differential that actively distributes torque between the rear wheels for optimal cornering precision.

In Edmunds performance testing, an S5 coupe equipped with the automated manual transmission (and pre-programmed launch mode) accelerated from a standstill to 60 mph in just 4.6 seconds, a quick time compared to its German rivals. The convertible did the same job in a fully competitive 5.3 seconds.

EPA-estimated fuel economy for the S5 varies depending on the choice of a hardtop or convertible and on which transmission you choose. The manual-transmission coupe is EPA-rated at 20 mpg in combined driving (17 city/26 highway). The coupe with the automated manual is rated at 21 mpg combined (18 city/28 highway), and we managed a surprising 23 mpg on the diverse 120-mile Edmunds evaluation loop. The automatic convertible checks in at 21 mpg combined (18 city/26 highway).

The 2015 Audi S5 comes standard with antilock disc brakes, stability and traction control, front-seat side and knee airbags and (for the coupe) full-length side curtain airbags. A blind-spot monitoring system, rearview camera and front and rear parking sensors are standard on the Prestige trim and optional on Premium Plus via the Technology package. In addition, the Prestige trim is eligible for an adaptive cruise control system (via the Driver Assist package) that includes an audible warning and brake intervention (under 19 mph) if a frontal impact is imminent.

In Edmunds brake testing, the S5 coupe and convertible came to a stop from 60 mph within a foot of one another at 108 and 109 feet, respectively, both solid performances among comparable cars with summer tires.

Driving the S5 is a remarkably low-impact experience considering its performance potential and capabilities. This Audi is easy to live with everyday, yet it's ready to thrill whenever you get the urge. Power from the supercharged V6 is plentiful, and unlike many V6 engines, this one is virtually vibration-free, even at redline. The standard steering system manages to be both calm on the highway and responsive in the turns. We also like the sport differential's understeer-quelling magic at the limit, though you won't get much use out of this feature unless you're comfortable taking corners with all four tires squealing.

Shoppers who choose the coupe's stick shift will be rewarded with precise, positive action through the gates. That's no knock on the automated manual, however. Audi's dual-clutch seven-speed S tronic transmission supplies silky-smooth shifts in normal driving, yet reacts quickly to paddle-shift commands and executes rev-matched downshifts with clinical precision.

Even with the Audi S5's sporting personality, ride quality remains quite pleasant overall. The optional adaptive suspension gives the driver some choice in the matter, but we feel the standard calibration strikes a highly agreeable balance between comfort and control. Whether you're on a twisty mountain pass or in the midst of a cross-country trek, this handsome two-door is a most rewarding traveling companion.

As expected from Audi, the S5's interior is highly appealing, boasting a tastefully understated design and high-quality materials. Actual functionality, however, can be hit-or-miss. For example, the standard dash-mounted MMI controller isn't nearly as easy to operate as the console-mounted controller you get with the Technology package. The upgraded system also features simplified menus and a slightly larger screen.

The S5's standard front sport seats are quite comfortable on long road trips, yet they also provide plenty of lateral support to keep you planted in corners. Some may be disappointed to learn that the convertible's optional neck-warming vents come with less sporty chairs, but unless you plan to toss your luxury convertible into sharp corners on a regular basis, you likely won't notice much of a difference. Either way, the rear seats offer scant head- or legroom for full-size passengers, so they're suitable only for smaller riders or cargo.

The Audi S5 convertible requires few practical compromises relative to the coupe. The tight-fitting, multilayer top requires about 17 seconds to lower and 15 to raise, and it's so well-insulated that you may forget you're driving a convertible. With the top stowed, the convertible's trunk can still accommodate 10.2 cubic feet of cargo, which is only 2 cubes less than that of the coupe. Like the coupe, the convertible features folding rear seatbacks for added convenience.