THE office building at 575 Fifth Ave. has been quietly turned into a commercial condominium by owner MetLife.

The 35-story tower on the southeast corner of East 47th Street has been divided into four pieces, three of them retail.

When it was sold by developer Sterling Equities and Credit Suisse in July 2005 for $376.3 million, it was measured under the then-rentable 522,346 square feet. The condo documents now measure it at 399,621 square feet.

The main tenant is L’Oreal, which occupies 389,000 feet through 2012, and Barney’s, which last year renewed its lease for around 40,000 feet. Women’s clothing chain Ann Taylor had been among the retail tenants.

The office condo now consists of floors eight through 11 and floors 14 through 40, while the three retail units encompass the concourse through third floors.

According to Building Department permits, behind the plywood fencing, architectural firm Gensler is reinventing the retail atrium with the addition of a small mezzanine.

In the concourse space, there is a yet-to-be-announced restaurant/cafe with an occupancy for 123 people, and another restaurant with an occupancy for 241.

The building is on a ground lease once owned by both Equitable Life and Cosmair, L’Oreal’s parent. That has been extended to Aug. 31, 2045, to be signed over to MetLife at closing.

The property was built in 1985 on the site of an old EJ Korvette’s department store.

Splitting buildings into condo parcels has proven to be a good strategic move as these can be sold separately. Retail pieces are especially lucrative on Fifth Avenue.

A MetLife spokesman didn’t respond to requests for comment, while broker Robert K. Futterman & Associates, which is offering the ground and second-floor retail spaces for rent did not return calls.

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There are so many available storefronts that brokers are resorting to giving away cars to cut deals.

“Bring the deal & take the wheel,” proclaims an upcoming ad for the 2,400-foot ritzy Jewel Mile townhouse at 717 Madison Ave.

Situated between East 63rd and 64th streets, the property is near Kwiat and opposite David Yurman, Mauboussin and Graff. The marketing campaign by Faith Hope Consolo and Joseph Aquino of Prudential Douglas Elliman advises that the broker whose retail tenant signs a $2 million deal for the duplex storefront could walk away with a $25,000 Mini Cooper.

“Bring us your max and you’ll get a Mini,” laughed Aquino, who convinced his European property owners to toss in the keys to the car on top of the usual broker fees, which could run to $800,000 for this deal alone.

The windowed, duplex store has 1,900 feet per floor plus a basement of 600 feet.

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After scouring all the trophy “Country Club” towers, CQS, a British hedge fund with $2 billion under management, signed a lease right after New Year’s for a 4,000-foot office that started at $115 a foot.

The deal at Carnegie Hall Tower is for a portion of the 41st floor that overlooks Central Park.

Paul Revson with Studley brought the ten ant to the Rock rose- owned building, which is represented by Billy Cohen and Matt Leon of Newmark Knight Frank. [email protected]