When Jaguar hits the streets for a test run, it is usually camouflaged somehow and done as discreetly as possible. By when a super-secret vehicle like their concept XFR-S supercharged sedan needs to be kept under wraps, they simply wrap it in another car entirelly. If you have ever heard of a "mule" car, this is what people are referring to.

How does this work exactly? The drivetrain and engine of a test vehicle is simply placed in an existing model. For XFR-S, Jaguar used the body of a Jaguar XF at the track, that car is currently available at Manhattan Jaguar NYC in New York, NY.

XFR-S is a supped-up RS version of the XF, and the tests at N?rburgring went extremely.  However, well trained photographers saw through the guise of a regular XF, and new just what it was. Nothing official about the car has been release, as it is still in testing mode before eventually hitting up more world wide car shows and evenutally dealer lots.

World Car Fans expects the Jaguar XFR-S "to be introduced sometime around late 2012 or early 2013."¹

Source: ¹http://www.worldcarfans.com/111081935858/2013-jaguar-xfr-s-mule-spied-for-the-first-time