Hips don't lie – this is the king of the hill of the A3 lineup.

“Good things come to those who wait” is what Audi is probably saying to people asking for a new RS3. The latest-generation A3 debuted nearly a year ago and was followed six months later by the hot S3 in both hatchback and saloon formats. The pinnacle of the A3 lineup will arrive by the middle of the year in the form of a new RS3. In the meantime, our spies have caught the five-cylinder, four-door machine conducting winter tests.

If it weren’t for the chunkier front air intakes and oval exhaust tips at the back, you’d be hard-pressed to identify this A3 model as the fully-fledged Audi Sport variant. The wings are a tad wider and the brakes are also bigger, but to the untrained eye, this prototype doesn’t look all that different compared to an A3 S Line or S3 model.

Gallery: New Audi RS3 Sedan spy photos

It has that typically understated styling RS models from Ingolstadt are known for, but if you really know where to look, the upgrades are visible. For example, the S3’s front bumper air intakes are very much fake whereas the RS3’s seem to be functional and are flanked by additional vertical slats to reroute the air.

The spy shots depicting the side profile reveal the prototype rides a tad lower than a lesser A3-based model while the back shows a more prominent trunk lid spoiler. The RS3’s party piece remains concealed under the bonnet where the five-cylinder turbocharged petrol engine produces at least 400 bhp.

We’ve heard through the grapevine Audi has massaged the inline-five 2.5 TFSI to deliver 415 bhp and there’s a wild rumour suggesting a hotter version is planned with 450 bhp. If that number turns out to be true, it will allow the Four Rings to recapture the title for the most powerful compact car it lost to Mercedes-AMG and its bonkers 416-bhp CLA45 S.

We’ll have to wait a few more months to see those last bits of camouflage come off and reveal the car in full. We are hoping Audi is going to unveil both the hatchback and saloon as it did with the S3 models rather than prolonging the wait for the four-door model.