The 2017 model year of the A4 brought a revamped, sleeker look and feel, and a few years later, the 2020 edition arrived with updated technology features. All together, these tweaks ushered the A4 into the ring with once untouchable contenders like the BMW 3-Series, the Mercedes-Benz C-Class and the Infiniti Q50.

Now, the A4 is lighter, more modern, peppier and more playful, too. Under the hood of 2017 and newer models is a 2.0-liter, turbo-4 engine with a 7-speed dual-clutch transmission that puts out 201 hp on the standard FWD variant or 261 hp for its AWD counterpart.

Front and rear five-link suspensions have been reworked to make for a smoother ride, and the A4 also boasts an electromechanical power steering system that automatically adjusts its ratio according to the car's speed and steering angle.

Also available on newer A4s is Audi's “Drive Select” system, which allows for the ability to manually tweak the vehicle's shocks, steering and throttle.

The 2021 Audi A4 and S4 are available in three trim levels: Premium, Premium Plus and Prestige, which start at $39,100, $43,800 and $49,400, respectively. The standard A4 is equipped with one of two four-cylinder engines, while the S4 is equipped with a V-6. Most will be satisfied with the standard A4 Premium trim, which comes with a powerful engine and a long list of tech amenities.

The A4 boasts a well-engineered ride that travels smoothly over uneven roads and offers a decent combination of ease and agility. The car responds crisply and the handling is sporty, and Audi's iconic Quattro all-wheel-drive system comes standard on all A4 variants as are an additional 13 additional horsepower in both A4 sedan engines. 

Powering the line's performance-savvy S4 variant is a 349-hp, 3.0-liter turbocharged V-6 with an 8-speed dual-clutch automatic and 369 pound-feet of torque.

As far as fuel economy goes, the A4 gets 24 mpg in the city and 31 mpg on the highway, which is actually excellent for an all-wheel-drive vehicle. The S4 version performs better but at the price of a slightly lower efficiency: 20 mpg in the city and 28 mpg on the highway.

Forward-collision alerts with automatic braking, lane-keeping assistance and adaptive cruise control with stop-and-go ability, a rearview camera and LED headlights with automatic high beams are among the A4's new list of safety features, too.

Optional safety add-on features include blind spot monitoring, rear-cross traffic alert, adaptive cruise control with stop-and-go ability, lane-keep assistance, traffic jam assistance, front and rear parking sensors, parallel parking assistance, a 360-degree parking camera system and traffic sign recognition.

The 2021 Audi A4 sedan received a five-star overall safety rating from the National Highway Traffic Safety Administration, having scored five out of five stars in the side impact and rollover tests and four out of five stars in the frontal crash test. The A4 also received the highest rating of “good” in all six crash safety tests from the Insurance Institute for Highway Safety.

In the A4's world of infotainment, Audi now provides a 12.3-inch digital instrument panel, as well as a revamped infotainment system that replaces the controller knob found on earlier models with a 10.1-inch touchscreen.

Audi's in-house “Multi-Media Interface” system – or MMI for short – comes standard and is easy to use, with a 10.1-inch touchscreen that sits high on the dash for convenient access and a menu that's well-thought out and makes sense. Replacing the traditional gauge cluster is a digital display that can be customized to show vehicle information, climate and audio settings and such, which comes standard on the Premium Plus and higher trim models.

Other standard infotainment features on the A4 include wireless Apple CarPlay, Android Auto, Bluetooth, two USB connections, HD Radio and a 10-speaker audio system. On the menu of add-ons are a 12.3-inch digital instrument cluster – which Audi calls its “Virtual Cockpit” – and a 19-speaker Bang & Olufsen audio system, too.

Other standard functionality and design features on the A4 include remote keyless entry, push-button start, three-zone automatic climate control and a sunroof.

Inside, the A4's interior is elegantly constructed of high-quality stock that includes leather upholstery, eight-way power-adjustable and heated front seats, ambient interior lighting and aluminum trim, all of which come standard. Up to five passengers ride comfortably, including the driver, but the front seats allow for a bit more room than the rear.

As far as cargo space goes, the A4's trunk measures 12 cubic feet, which is typical for small luxury cars. Audi also included a split-folding 40/20/20 rear bench that folds down to make room for lengthier pieces of cargo, too.

Compared to the BMW 3 Series, both sedans are rigged with powerful engines that make for an exciting drive. The A4's cabin materials are swankier than the 3 Series, however, and more safety features are offered as part of the standard package on the A4. Compared to the Mercedes-Benz C-Class, the A4 is slightly larger but only by a few centimeters, which makes a big difference when it comes to leg room but doesn’t weigh down the car’s zippy performance. Compared to the Infiniti Q50, the A4 handles better, gets better gas mileage, comes with all-wheel-drive and is also priced about $5,000 less than the Q50, too.

The base price of the 2021 Audi A4 sedan is $39,100, which is slightly higher than the norm for a luxury compact car. The base Premium Plus trim costs $43,900, while the tier-topping Prestige variant goes for $49,400.

The sportier performance take on the A4, the S4 also comes in three trim levels: Premium ($49,900), Premium Plus ($53,500) and Prestige ($58,200). Standard on all S4 variants is a  349-horsepower V-6 engine, an eight-speed automatic transmission, a sport-tuned suspension and 12-way power sport seats in the front that also give massages.  The S4's standard features are identical to the rest of the A4 line, too.

These days, used A4s are fairly simple to find – given the car’s optimal resale value – and major savings to be had by opting for a used model over a new one. Depending on the model year, mileage and trim package, used A4s tend to hover in the range of $15,000-$25,000 but can go for as little as $10,000. It just goes to show the value in choosing a used car instead of buying new.

Whether you decide to go with the Audi A4, another Audi model or another sedan altogether, Shift makes purchasing a quality used car easier than ever. That's because buying any of Shift's cars is literally as easy as the click of a button directly online from the comfort of your home. 

Whatever make and model of sedan you choose, you can rest assured that you’re getting a fair, up-front price from the get-go and that it has no hidden issues, thanks to Shift's rigorous 150-point inspection, too.