Mercedes-AMG has unveiled the GLC 53, a new six-cylinder rival to the Audi SQ5 and BMW X3 M50 that marks a clear shift in its strategy and spells the end for the four-cylinder GLC 43 and 63 SE Performance models. 

Due in the UK later this year, the 53 will be the only hot version of the GLC until a new electric model with advanced axial-flux motors joins the range in 2027. 

Its arrival comes as new regulations, including the forthcoming Euro 7 emission standards, have rendered obsolete the four-cylinder engine used by the GLC 43 and GLC 63 S E Performance. 

It also underlines a new direction in strategy as Mercedes-AMG forgoes plug-in hybrid powertrains, as used by the previous GLC 63 and the E53 saloon, for a new mild-hybrid set-up that emphasises its combustion engine. 

The GLC 53 combines a reworked version of Mercedes' turbocharged 3.0-litre straight-six engine with a 48V starter-generator mounted in the gearbox. 

The starter-generator can provide a boost of up to 22bhp and 151lb ft, combining with the engine to put out a system total of 449bhp and 443lb ft. An overboost mode can increase torque reserves to 472lb ft for up to 10 seconds per activation. 

This represents increases of 34bhp and 103lb ft over the outgoing GLC 43, cutting its 0-62mph time by 0.3sec to 4.2sec. 

The top speed is artificially limited to 155mph but can be extended to 168mph with an optional AMG Driver's Package. 

Beyond its raw performance, the new GLC 53 aims to appeal with its acoustic character. Mercedes-AMG says it has focused heavily on the response and sound of its six-cylinder engine, a development of that used by the E53. 

The firm has fitted a new cylinder head, intake system and an exhaust with "special resonators" that promise "characteristic crackling" and "AMG-typical" pops and bangs. 

The engine comes with a nine-speed automatic gearbox and four-wheel drive, which can send up to 100% of drive to the rear axle. 

For the first time on an AMG SUV, an electronic rear limited-slip differential is available as part of an optional package, which also adds a drift mode. 

Meanwhile, a rear-wheel steering system - offering up to 2.5deg of articulation adaptive damping and variable-ratio steering aim to boost agility. 

Prices have yet to be confirmed, but the GLC 43 starts from £76,715 and the GLC 63 is priced from £125,185, so they are likely to kick off at around £100,000.