SPY PICS: Porsche's most focussed 911

This isn't the first time we've seen the highly-anticipated Porsche 911 GT3 RS, but when the most powerful naturally-aspirated Porsche 911 rears its head for cold weather testing it gets people talking.

Porsche's newest RS takes the 'regular' new 911 GT3 – which we just drove at its local launch, after which Editor in Chief Mike Sinclair praised "the engine, the handling, the whole box and dice" — to a whole new level and is shaping up to be one of the most engaging performance cars ever seen from Zuffenhausen.

Although Porsche is still keeping the technical details of the new model a secret, the revealing spy photos show several differences from the regular 911 GT3, including pumped wheel-arches with brake cooling ducts fore, and larger air intakes aft along the cars flanks.

There's a huge rear wing that is slightly different to the one seen in April 2014, featuring more advanced struts, and together with a deeper front splitter the car's track-tuned aerodynamics should deliver even more down-force.

Big wheels and huge disc brakes gripped by massive yellow callipers counter the racer-for-the-road's engine performance, which will come from a more potent version of the GT3's non-turbo 3.8-litre boxer six.

In the standard GT3, the high-revving horizontally opposed six-cylinder engine has a tropospheric 9000rpm redline, and the RS model could take that even higher. The GT3 belts out 350kW/440Nm and that could easily reach 375kW or more in the RS — more than 500hp.

As such, expect 0-100km/h acceleration in less than 3.5 seconds and a top whack of around 320km/h, or almost 200mph.

We previously reported that the car was expected to make its debut at the 2015 Frankfurt motor show in October, but considering based on its production-ready looks during this cold-weather test, there's a chance it could be revealed earlier — potentially at the 2015 Geneva motor show in March.

Porsche will be hoping its new GT3 RS won't suffer the same overheating glitches that affected the GT3 when it first arrived here earlier this year, after which all five Australian-delivered GT3s were recalled to have their engines replaced.