The Audi A4 is an appealing compact luxury sedan with the cachet of the Audi name and the inherent goodness of German engineering. So, what's the S4? Well, it's just that much better.

The 2018 Audi S4 is also better than the car it replaces. Under the hood sits a longitudinally mounted, twin-scroll turbocharged 3.0-liter V-6 that produces 354 horsepower and 369 pound-feet of torque. That's a gain of 21 hp and 44 lb-ft of torque over the outgoing supercharged 3.0-liter V-6, and the torque is available earlier, its peak coming on at 1,370 pm and holding steady until 4,500 rpm.

Audi says all that power can vault the S4 from 0 to 60 mph in just 4.4 seconds.

That engine is mated to a new 8-speed automatic transmission that replaces both a 7-speed dual-clutch transmission and a 6-speed manual gearbox (bummer on the latter). From the transmission, the power flows to all four wheels via Audi's quattro all-wheel-drive system, which sends 60 percent of the power to the rear during normal driving to provide a rear-drive feel. Up to 70 percent of the torque can go to the front, and up to 85 percent can to go to the rear. An available Sport Differential can send all of the available power at the rear axle to the outside wheel in turns to help the car rotate.

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Audi has redesigned the five-link front suspension for better dynamics. The S4 rides the same MLB Evo platform as the A4, but it sits 0.9 inch lower, and Audi offers active dampers as part of the S Sport package. Dynamic steering is also available. It adjusts the steering ratio based on vehicle speed. The standard Audi Drive Select system offers Comfort, Auto, Dynamic, and Individual driving modes that allow drivers to change the gear shift points, steering weight, throttle response, adaptive cruise control, and, when ordered, damper settings.

2018 Audi S4

2018 Audi S4

2018 Audi S4

2018 Audi S4

2018 Audi S4

2018 Audi S4

Inside, the S4 gets a flat-bottom steering wheel with shift paddles; heated 8-way power-adjustable front sport seats with 4-way power lumbar support, power side bolsters, and a massage function; diamond-stitched leather upholstery; and three-zone automatic climate control. A dual-pane sunroof is optional.

The tech features are abundant. Apple CarPlay and Android Auto are standard. Audi's virtual cockpit, which is a digital infotainment display in the instrument panel, is optional. The virtual cockpit offers Google Earth navigation, which is supported by a 4G LTE connection. It also comes with a sport display mode that makes the tach and speedometer prominent and adds a boost gauge and lap timer.  Also optional are a color head-up display, the MMI touch interface with handwriting recognition, and a Bang & Olufsen 3-D sound system.

Standard safety features include forward collision warning with emergency braking and pedestrian detection. Also available are blind spot warnings, adaptive cruise control with stop and go, and a system that prepares the car for a crash from the rear, warns the occupants when exiting the car if a cyclist is approaching, and includes rear cross traffic alerts.

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Perhaps the least impressive change to the 2018 S4 is the exterior, but it, too, is upgraded. It takes on the evolutionary new look, with slightly crisper lines that echo those of the last model. The headlights are full LEDs and the daytime running lights and taillights are also LEDs. The S4 is differentiated from the A4 by its 18-inch double-spoke wheels with standard summer tires (all-seasons and 19s are optional), quad exhaust outlets, trunk lid lip spoiler, platinum gray singleframe grille with aluminum-look bars, and aluminum-look side mirrors. Those side mirrors are auto-dimming, power folding, and heated. Red brake calipers are offered in the S Sport package.

The 2018 Audi S4 goes on sale this spring with a starting price of $51,875 for a Premium Plus model and $56,775 for a Prestige model.

For more on the Audi A4 range, read the in-depth reviews at The Car Connection.