Via West Coast Pirate, who first did the research on this, comes this ad. West Coast Pirate explains:

This is is a car advertisement from Germany. When they finished filming the ad, the people who made it, noticed something moving along the side of the car, like a ghostly white mist.

If you turn up the sound, you can also hear whispering. The ad was never put on TV because the unexplained ghostly phenomenon frightened the production team out of their wits. Watch it and about halfway through (after the car comes from behind the trees) look closely and you will see the white mist coming up from behind the car and then following it along the road!

Watch the disturbing ad here.