Next-generation Golf will be based on the VW Group's MQB platform. The Golf MkVII is expected to make its debut sometime in 2012.
Here are a set of spy shots of a next-generation Golf VII test mule breaking a sweat at the Nurburgring Nordschleife circuit.
The 2013 MkVII Golf chassis sits underneath this vehicle, which on the outside is still dressed in the Golf's current body form, hence no need for any camouflaging.
Now, one may ask, since the current Golf generation, the MkVI, was only released in 2009, why the rush into testing the next generation?
The answer to that is that the 6th generation Golf is still based on the same Volkswagen PQ35 platform that its predecessor was - making it more of a major facelift with body style changes than a true generation jump. The 7th generation Golf (MkVII) will be based on the entirely new MQB platform ("Modular Querbaukasten" in German), which is why there will likely be only a little more than 3 years between the two.