The test mule snapped appears to the be the same one we saw in Sweden late last month undergoing extreme winter testing. It features the side intakes on the rear haunches which draw air through the twin intercooler set-up.
Like the existing 911 Turbo, the 991 Turbo will feature a twin-turbo flat-six engine. Specific power outputs haven't been finalised yet but rumours and reports suggest up to 600hp (448kW) could be on offer.
With the traditional all-wheel drive system, it's likely Porsche will be chasing Nissan's benchmark in 0-100km/h times. The Nissan GT-R famously manages the sprint in 3.0 seconds, the new Porsche is expected to equal or better that feat.
We're still not sure about what is going on with the rear spoiler of the new Turbo, whether or not Porsche will fit one is still up in the air. The company may be working on a hydraulic slimline design we've become used to on later Turbo models.
Porsche is set to unveil the new 991 2012 Porsche 911 Turbo at next year's Geneva Motor Show in March. Entry-level 2012 911 models are said to debut at the 2011 Frankfurt Auto Show in September.