SPY PICS: Mercedes-Benz MLC 63 AMG

Mercedes-Benz's answer to the unexpectedly popular BMW X6, the MLC, has been spied both in the US and Germany and has even been seen in range-topping AMG form.

But now fresh pics of the rarer MLC 63 AMG super-SUV have emerged from near the Mercedes-Benz R&D centre in Sindelfingen, revealing more of Merc's first direct competitor for the X6 M.

According to the Automedia snappers, this pre-production MLC-AMG, which looks more like the Concept Coupe SUV revealed at the 2014 Beijing motor show, was being used to test airbag functions, hence the removal of its front-end cladding.

That makes AMG's trademark single-bar grille visible for the first time, along with the top MLC model's more aggressive front bumper intakes, while features like prominent side skirts, quad exhaust outlets and low-profile tyres on racy alloy wheels remain on show.

Like the ML 63 AMG on which it's based, the top-shelf MLC -- which some reports suggest could be called the ML-Coupe or M-Class Coupe -- will be powered by AMG's twin-turbo 5.5-litre V8, which summons up 410kW/760Nm in base form and 430kW/800Nm in up-sec 'S' guise.

However, some reports suggest AMG's all-new downsized M178 4.0-litre twin-turbo V8, which will debut with 375kW/650Nm outputs in the upcoming Mercedes-AMG GT coupe, could be fitted instead of the M157.

While that would make it more efficient, it wouldn't deliver a significant performance advantage over the X6 M, which packs a 408kW/680Nm 4.4-litre twin-turbo V8. However, those figures are likely to rise in the new X6 M, based on the second-generation X6 due here this year.

Either way, the V8 will send its power to all four wheels via Benz's 4MATIC system and a new nine-speed automatic transmission.

Expect AMG's 23nd model – including the new flagship GT coupe, to be revealed at the Paris motor show in October – to be released following the standard MLC, which may lob at next January's Detroit show.

-- with Automedia