A year ago, Nest Labs bought a retired fire truck off a Craigslist posting in Michigan, painted it blue and sent it across the country. Starting on Friday, the company, acquired by Google in January, is camping the truck in downtown Manhattan for the holidays as a promotional staging ground for its devices.

It's the next step in the smart-home outfitter's maiden marketing campaign, called "Thoughtful Things," which began with a series of TV and print ads in November.

The truck is equipped with installations to demonstrate its internet-connected smoke detector, Nest Protect. Passersby can buy the Protect right there, along with Nest's thermostat and video camera. The truck also hosts free smartphone charging, gift-wrapping and kids' firefighter hats.

"Everybody loves fire trucks," said Doug Sweeny, VP-marketing. Kids do in particular, he said; the truck has visited some 40 schools, a bid to reach Nest's target market of middle American families. On its tour, the company has relied heavily on guerilla marketing -- the truck has pulled up a street festivals and at an outdoor screening of Disney's "Frozen." Mr. Sweeny described the truck as his "Swiss-army knife," capable of executing several marketing objectives at once.

Elsewhere in Manhattan, Nest placed a large, acrylic box with warnings about the dangers of carbon monoxide. Next year, the company is bringing its promotional truck to Europe -- in France, home smoke detectors will be compulsory in 2015 -- and pursuing other experiential marketing campaigns.

For this effort, Nest worked with West Coast Customs, the car remodeling company behind MTV's "Pimp My Ride." Nest shunned agency partners. "We could have hired an agency," said Mr. Sweeny, "and it would have cost a lot of money."

The Nest truck is parked a block from Google's Manhattan headquarters, but, like its commercials, the truck bears no mention of its deep-pocketed parent.