The 2018 Audi S4, like almost every sedan these days, faces a challenging marketplace overrun with the crossovers that consumers have adopted en masse. And Ingolstadt hasn’t made things any easier for the S4, which shares showroom real estate with both Audi’s SQ5 SUV and the S4’s shapelier and slightly more capacious sibling, the new S5 Sportback. While the S4 remains a go-to for under-the-radar performance and luxury for proponents of the traditional three-box, sports-sedan formula, its wider allure is waning.
Now based on the latest-generation Audi A4 sedan, the revised-for-2018 S4 shares much of its makeup with the SQ5 and the S5 Sportback, including its Volkswagen Group MLB Evo platform and a turbocharged 3.0-liter V-6 engine mated to an eight-speed torque-converter automatic transmission. (Audi unfortunately has axed the six-speed manual from the order sheet with the new generation of S4.) Quattro all-wheel drive is standard, with the S4 defaulting to a 40/60 front-to-rear torque bias; the system can shuffle up to 70 percent of the grunt to the front axle or 85 percent to the rear as traction demands. Compared with the previous S4’s 333-hp supercharged 3.0-liter V-6, the new mill churns out 354 horses and 369 lb-ft of torque at a low 1370 rpm.
Weighing 89 pounds less than the last S5 Sportback we evaluated, our S4 test car returned the same 4.3-second zero-to-60-mph sprint as the S5, as well as a quarter-mile pass of 12.8 seconds at 109 mph—0.1 second and 1 mph quicker than the Sportback. The SQ5 needed 5.1 and 13.7 seconds for the same measures. More important, the sedan’s times are both 0.6 second quicker than those of the previous S4 and fleet enough to better all of its key competitors save for the Mercedes-AMG C43 4Matic sedan, which just edges out the Audi with a 4.1-second blast to 60 mph and a quarter-mile in 12.7 at 110 mph.
Rolling on standard 18-inch wheels (19s are optional) shod with 245/40R-18 Hankook Ventus S1 Evo2 summer tires, the S4 also returned an impressive 0.99 g of lateral grip on the skidpad and a 148-foot stop from 70 mph, although we should note that the 501-pound-heavier SQ5 matched its braking performance. Similarly, the S4’s observed fuel economy of 20 mpg overall and 28 mpg on our 75-mph highway fuel-economy test merely equaled the efficiency of the portlier SUV. The S5 Sportback, which shares the S4’s EPA estimates—21 mpg city, 30 highway, and 24 combined—fared notably better at 23 mpg overall and at 33 mpg on the interstate.
What the S4 lacks most is character, which is fine for a stealthy sleeper but less so for a driver’s machine. It does not do theater. Whereas the previous supercharged V-6 had a snarl in its voice and a crispness to its responses, the turbo engine, while more powerful and plenty willing to rev to its 6750-rpm redline, feels and sounds dulled in comparison. The eight-speed automatic gives up little if anything to the old car’s seven-speed dual-clutch unit, providing more fluid low-speed behavior yet with similarly coordinated and lightning-quick shifts. Responsiveness to the small, steering-wheel-mounted paddles is not quite as instantaneous, though. Dropping the shift lever into S wakes up the whole powertrain for aggressive driving, but the setting’s reluctance to cruise in top gear and eagerness to downshift and hold revs can feel a bit too eager for anything less than a flat-out pace.
Our test car was fitted with Audi’s $1150 variable-ratio Dynamic Steering system, which provides precise and super-direct action for the driver, but we probably could live without it. We haven’t driven an S4 equipped with its standard fixed-ratio setup, but the Dynamic helm always felt a bit artificial and stingy on the tactile feedback that we’ve praised in other sporty sedans such as the 10Best Cars–winning Alfa Romeo Giulia. The S4’s fine balance of solid body control and taut-but-tolerable ride quality on most surfaces also at no point had us wishing for the bigger 19-inch rollers. However, the torque-vectoring rear Sport differential, part of the $2500 S Sport package that also includes red brake calipers and adaptive dampers, is a worthwhile upgrade. It compensates for the S4’s inherent understeer at the limit—partially attributable to 56.6 percent of its 3928 pounds sitting on the front wheels—by modulating torque across the rear axle to tighten the car’s line into and out of corners. Additional configurability comes via the selectable driving modes (Comfort, Auto, Dynamic, and Individual) of the Audi Drive Select system, which can vary the responsiveness of the steering, engine, and drivetrain as well as the firmness of the dampers. Yet, from behind the wheel, it just drives like a quicker A4, with none of the S4’s kit really endowing it with a feeling of specialness.