It's been a few years since we got our first look at the all-new Mercedes-Benz C-Class undergoing prototype testing, but the luxury compact sedan isn't quite ready to break cover just yet. Following the debut of the regular C-Class, more powerful AMG variants will inevitably follow.

Now, our spies have caught Mercedes testing the upcoming AMG C53, a new model that will reportedly replace the current AMG C43 and compete with the BMW M340i and Audi S4. While the camouflage hasn't dropped since our last look at the new Mercedes AMG C53 prototype, testing has progressed from snow trails to sunny city streets in Southern Europe.

Even though the prototype is heavily camouflaged, we can immediately tell we're looking at the hotter AMG C53. Lurking under the camo is AMG's signature Panamericana and a bumper with larger, more aggressive air intakes than the regular C-Class. The track also looks wider, the wheels are larger, and we can also see some beefier brakes hinting at its performance capabilities. This prototype still appears to be at an early stage of development, however, as AMG's distinctive rectangular exhaust pipes are nowhere to be seen.

Currently, the C43 AMG model is powered by a 3.0-liter twin-turbo V6 producing 385 horsepower and 384 lb-ft of torque.

The C53 that's rumored to replace it is expected to use the same 2.0-liter four-cylinder turbocharged engine as the Mercedes-AMG A45 S hot hatch. In the A45 S, this unit produces 416 hp and 369 lb-ft of torque. The next-generation AMG C63 is also rumored to ditch its twin-turbo V8 for an electrified four-cylinder unit with hybrid technology that will produce over 500 hp combined.

We could be waiting a while for the new Mercedes-AMG C53 to break cover. The regular next-generation Mercedes C-Class is expected to debut later this year, so the hotter AMG variants will likely arrive sometime in 2021.