It’s a wonder nobody crashed their real cars doing a double-take at a glowing Audi that seems like an apparition, appearing in a fog and then disappearing just as quickly. German ad firm Thjnk came up with this ephemeral ad campaign for the hybrid-electric Audi A7 Sportback h-tron quattro to highlight the fact that nothing but water vapor comes out of its exhaust.

“We asked ourselves, where do you place ads for the most environmentally friendly and progressive engine Audi has ever built? Nowhere. So for the car that leaves nothing behind but vaporized water, we created ads that leave nothing behind but vaporized water.”

Though the agency doesn’t specify how the effect was achieved, it seems that an LED image is projected onto water vapor to get that ghostly look. The ads were placed in busy areas of big cities at night, flashing briefly and then vanishing.

Check out 300+ other creative advertising campaigns, from guerrilla marketing to controversial ads using revolting imagery and graphic content to hawk hand soap, nose trimmers and other products and services.

At its best, advertising is entertaining, even useful. At its worst, it is invasive, abrasive, and perhaps even offensive. IBM’s new campaign from Ogilvy France skirts the line, featuring public objects that are useful but which somewhat invade the urban space.

The Smart Ideas for Smarter Cities campaign includes three billboards that extend out from city walls and into the urban environment. One is an awning of sorts, providing a dry space for residents to get out of the rain or a bit of shade to get out of the sun.

Another is a small bench which gives weary pedestrians the chance to sit down for a moment. The last is a ramp that covers a portion of a small staircase, letting cyclists or luggage-wheeling residents take an easier route.

The campaign is meant to inspire viewers to think differently about their cities and how some elements could be tweaked to be more useful for residents. It’s something of a risk, however, since this invasion of the urban environment may not be welcomed by residents who think that advertising is already too ubiquitous on city streets.

(images via: Fast Company)