Enlarge (credit: Aurich / Audi)

It’s been an interesting year behind the wheel here at Cars Technica. Quite a few of the cars I’ve tested have delivered surprises—underwhelming ones in the case of best-sellers like the Toyota Camry and Nissan Rogue, as well as unexpectedly delightful ones like the Kia Niro and Honda Accord. Think of today’s story as a microcosm, then. It’s about two cars from the same OEM, built on the same architecture, similar enough to be cross-shopped. The brand is Audi, the cars are the 2018 A4 sedan and 2018 S5 Sportback, and the surprise? For that you’ll have to read on.

Neither car is a stranger to these pages. We first drove the A4 sedan back in 2016 at its launch, proclaiming it “for nerds, by nerds.” Our first taste of the more powerful, more expensive S4 sedan and S5 coupe came a year later, as did our first drive of the Sportback, a sleeker, yet practical, five-door alternative to the sedans. First drives are certainly informative, but you’ll learn a lot more living with a car for a week than you will sharing it for the day with another auto journalist. And over the summer, I had the opportunity to really get to know these four-ringed siblings.

The car I thought I’d love

OK, that subheading gives the game away, but it’s true: I did think the S5 would be the one I’d love. After all, it’s a Sportback—the name Audi gives to its five-door fastback sedans. My love for the five-door body style is well documented at this point; I spent my own money on a Saab 9-2x, and I’m a true believer that five door wagons, hatches, and fastbacks really do offer the most practicality while also looking better than almost anything else on the road.