Rob Thomas, Rev Run and Mr. Mariah Carey at First-Ever Mercedes-Benz Day

634442981265600000337940 46 arjoel1 062111 Rob Thomas, Rev Run and Mr. Mariah Carey at First Ever Mercedes Benz Day

Alexa Ray Joel—she was there, too.

Naturally, we sought out Nick Cannon—rapper, former Nickelodeon star and husband of Mariah Carey—at the grand opening of the Mercedes House on 11th Avenue last night.

“This is hot. It’s right by my house, so I’m good,” Mr. Cannon, who lives in Tribeca, told us. “… I love my Mercedes-Benz, I’ve owned since I was a teenager. I have a couple.”

Awesome.

The five-floor Mercedes House has a 330,000-square-foot Benz dealership on the ground-floors and luxury condos developed by Two Trees above. “The building is amazing, we’re really pleased with the building. … It’s been five years and a lot of work,” said a typically BroBo scruffy Jed Walentas, one of Two Trees’ principals, adding, “The Mercedes deal was incredible.”

Dude.

And, of course, given what was in the air, the promised surprise concert was… Matchbox 20. Had to be. The band that soundtracked your late 1990s performed on an outdoor stage before a seating area covered by a large, clear tent with white, fluffy couches, chandeliers and padded bleachers with pillows underneath.

They opened with a song called”How Far We’ve Come” (indeed), and lead singer Rob Thomas seemed stoked, man. “Just being outside in New York City and playing music for good people who have had a couple of drinks… It doesn’t get better,” he said. The crowd roared.

And drinks there were. The concert even came with a “Champagne tailgate” (which consisted of a Mercedes-Benz hatchback with a trunk full of Champagne flutes) and yet another open bar. It was like a college party all grown up and on a much larger (and more expensive) scale. There was no mosh pit—the crowd, dressed mostly in suits and cocktail dresses, was too classy for such behavior. This is Mercedes, after all.

Before the concert, guests gathered in the dealership, which was decked out like a wedding reception with white tablecloths and chair covers, flower-and-candle centerpieces and caterers wandering around with hors d’oeuvres. And of course, there were the cars.

Mercedes-Benz models lined the aisles, and guests could climb behind the wheels. Look at me! Mr. Cannon and Rev Run, of Run-D.M.C. fame, posed for pictures in front of a 1937 Mercedes-Benz roadster.

Dieter Zetsche, the chairman of Daimler AG and head of Mercedes-Benz Cars, declared during a speech that 11th Avenue is now to car dealerships what Broadway is to theater and eagerly welcomed “all competitors of the neighborhood.”

And City Council Speaker Christine Quinn, who said she was “pinch-hitting” for Mayor Bloomberg, who could not attend the event because of his mother’s death, went even farther than that. The new building was “the most beautiful and wonderful car dealership we’ve ever had in New York City,” and continued her adulation as she went on about the benefits to the neighborhood.

She then shouted: “On behalf of Mayor Bloomberg and the City of New York, today is Mercedes-Benz Day!”

Mark your calendars, kids.

pengel@observer.com