With the ongoing development of the W206 Mercedes-Benz C-Class, the higher-performance Mercedes-AMG C53 has been spotted testing again, this time in the warmer climate of Southern Europe.

The current line-up of Mercedes-AMG 53 models has so far been home to the M256 3.0 litre inline-six, which produces 435 hp and 520 Nm, along with an EQ Boost starter-alternator which is part of a 48-volt electrical system that contributes 22 hp and 250 Nm of torque.

This would be the logical progression from the current, W205-generation Mercedes-AMG C43, which is purely internal combustion and makes 385 hp and 520 Nm of torque from its M276 3.0 litre biturbo V6 engine. However, with the next-generation C63 reportedly set to replace the venerable V8 layout with an electrified 2.0 litre inline-four turbo unit, the C53 on the rung below isn’t likely to boast of a bigger engine, and therefore looks set to use the four-pot as well, according to our sources.

The headline act amongst the German brand’s four-cylinder engines is of course the M139 2.0 litre unit that powers the A 45 S and CLA 45 S with 421 hp and 500 Nm of torque. Numbers-wise, this provides a plausible basis for the C43 replacement, offering 36 hp more than the 3.0 litre V6, even though it is 20 Nm down on the larger engine.

Driveline details have yet to be confirmed, though the precedent for the C53 appears to be one of an all-wheel-drive application, given that both the current C43 and the electrically boosted AMG 53 range are AWD. As for the test mule seen here, much is still work in progress, particularly at the back where the tail lamps and exhaust outlets are interim parts.

The front end similarly leaves plenty to be worked on, as it wears considerable camouflage cladding on its bonnet, grille and front bumper, though the headlamps appear to be similar to those featured on the previously-sighted test mule in winter. With the main W206 C-Class range expected to debut late this year or early in 2021, this AMG C53, along with the range-topping C63 are expected to premiere a year later.