A PHer managed to grab these spy shots of a heavily disguised Mercedes being tested on Mont Ventoux in the south of France recently.
The car was filling up at a small garage when it was spotted. The photographer was specifically requested by one of the Mercedes people not to take pictures of it, so he had to sneak a few while the driver and support crews weren't looking.
In the words of our intrepid reporter: "One onlooker asked a Mercedes team member what the engine was and he scribbled something in the dust on the back of the car then quickly rubbed it out -- it looked like 3.1 or 3.2 and either V6 or V8. It sounded rather "sweet" and left the garage with a pretty good turn of speed.
"If anyone knows what it is could you let me know?"
We certainly will: speculate away...