Mercedes: No need for R when you've got a star

Mercedes gullwing SLS AMG GT3. Photo / Supplied

Mercedes' sexy gullwing SLS AMG GT3 reveal rather eclipsed details of the R-class facelift.

This is the brand's first GT3 racer and will sell to private buyers campaigning GT sprint and endurance classes.

A number of modifications have been made to the standard car. The underside is now smooth, while bodywork modifications exaggerate its contours, with carbon fibre body panels and lightweight polycarbonate glazing used to trim weight.

A new front apron features larger air intakes, with a transverse fin diverting air to the engine cooler and brake discs.

The bonnet nostril dissipates engine heat, while wing apertures vent hot air from the wheel arches - and more vents in the sills take cool air to the back brakes.

Those arches are wider, to accommodate the fat racing tyres, and there's even a fuel filler in the B-pillar to allow quick pit-stop refuels, with the 120-litre petrol tank positioned just behind the driver.

The car looks its widest from the rear, where an adjustable carbon fibre wing can be tuned to suit specific tracks.

What hasn't changed much is the engine. The dry sump 6.3-litre V8 tucked low down and behind the front axle is virtually identical to the road car's but tuned to put out around 447kW. It's mated to a six-speed sequential transmission and integrated multi-disc locking diff. The combination propels this much lighter car from zero to 100 in a claimed 3.8 seconds.

An aluminium double wishbone suspension with adjustable spring, damper, track width and camber, suspension height and stabilisers should make for an exciting drive. Happily, sports brakes with ceramic composite discs have been fitted.

Having trouble? A pneumatic jacking system integrated into the underbody lifts the car by 190mm to speed up wheel changes.

The cabin's as functional as you'd expect, and includes both a roll-cage and an integrated head and neck support device, with drink access and fire extinguishers activated via steering wheel-mounted controls.

The car will go on sale late this year, with homologation complete in time for next year's season. No word yet on whether it'll come in right-hand drive. Price is likely to mirror BMW's Z4 GT3 at about $570,000.

As for the R-class, it's had cosmetic tweaks and upgrades to the diesel engine aimed initially at the US, and will be available here late this year.