From supercars to underwear: Check out the perks that come with these mega-mansions

This mansion comes with 3,000 horsepower

In the super-competitive luxury real estate market, sometimes you need to supercharge your marketing strategy, literally.

When Douglas Elliman real estate broker Senada Adzem recently listed a 12,778-square-foot waterfront mansion in Del Ray Beach, Fla. for $13 million, she revved up the deal by adding 3,000 horsepower.

Ferrari included with the South Florida estate
Senada Adžem

The five-bedroom, seven-bathroom fully furnished residence comes with a 660-horsepower 488 Ferrari Spider (manufacturer's suggested retail price of $350,000) parked in the garage and a custom-built 2,508 horsepower Midnight Express power boat on the dock.

Bespoke powerboat included with Del Ray Beach home.
Midnight Express

Adzem says the bespoke speed boat with five engines is valued at approximately $1.6 million.

"It speaks to the type of lifestyle this multi-million-dollar estate represents in South Florida," Adzem tells CNBC. "Our clients love a little cherry on top of the deal."

Senada Adžem

Adzem and her seller hope the high-powered rides will draw attention to the Del Ray Beach home that also includes a dock on the inter-coastal waterway, a pool, Jacuzzi, four bars, and a hi-tech wine cellar that requires the owner's thumbprint for access.

The wine room with biometric lock
Senada Adžem

But Adzem claims it's not just a marketing ploy. "This is an actual convenience factor, so that someone doesn't have to wait for months and months for their custom Ferrari or years for their custom Midnight Express."

The view of the pool and hot tub in the backyard.
Senada Adžem

Adzem says if a buyer doesn't want the full "horsepower house package" the asking price for just the real estate — no car, no boat, no furniture and no art — is just under $8 million. So in reality, all the stuff that's included in this $13 million package deal will cost a buyer about $5 million.

Birdseye view of 706 Southeast 2nd St in Del Ray Beach
Senada Adžem

This isn't the first time Adzem has offered wheels with real estate. She tells CNBC that in 2017 she sold an oceanfront condo in Boca Raton, Fla. that included a Tesla and a Jaguar. The "wheel-estate" package went for just under $4 million.

1000 South Ocean Blvd condominium in Boca Raton, FL
Senada Adžem

"The buyers were thrilled not to have to go car shopping," says Adzem.

She isn't the only broker trying to drum up attention for a listing with a fancy set-of-wheels.

The backyard pool and view inside of the Beverly Hills estate that includes Warhol's Rolls Royce
Lamerica / Darran Assy

Next month in Los Angeles, Lamerica Homes broker Paul Wylie has plans to debut a five-bedroom, eight-bath listing in the Trousdale Estates section of Beverly Hills that will include the 1974 Rolls Royce Silver Shadow once owned by Andy Warhol.

The 1974 Rolls Royce originally owned by Andy Warhol
Lamerica / Darran Assy

"He purchased it in 1974, it's got 60,000 miles on it. He owned it until his passing in 1987, and living in Manhattan he didn't drive it very much," Wylie tells CNBC.

Along with the one-of-a-kind Rolls, Wylie says all the art inside the house is also included. Among the pieces are eight Warhols, including Jockey briefs with a dollar sign on the rear signed by the icon himself.

White cotton Jockey underwear with dollar sign screenprint signed by Warhol
Lamerica / Darran Assy

The 7,600-square-foot mansion with the classic Rolls, plus all the artwork will be offered at $17.75 million. If a buyer just wants the home with no wheels and no art the planned listing price is about $15.63 million.

Lamerica / Darran Assy

In Manhattan, Compass real estate broker Alyssa Brody is marketing a $29.5 million townhouse in the Chelsea neighborhood. She tells CNBC at that price the developer will park a brand new Bentley in the garage as a "signing bonus."

This NYC townhouse comes with a Bentley

While the high-octane marketing technique can garner attention and attract more eyeballs to the listing, the truth is, mansions with fancy rides "thrown in" don't sell themselves.

President of AKP properties in Los Angeles Aaron Kirman thinks the strategy is "gimmicky," however he understands why it's done.

"I could see why brokers and sellers do it, we need the press and media to help us sell houses, and sometimes you do things for that exposure and not necessarily for the actual buyer," Kirman tells CNBC.

Kitchen and dining area inside $36.8 million NYC townhouse.

That townhouse in N.Y.C. with the "bonus Bentley" scored tons of free press but hasn't found a buyer yet, even with a $7.3 million price drop from its original 2017 asking price of $36.8 million.

"People don't buy houses for cars, and as the house price drops the car will most likely be excluded from the sale," Kirman tells CNBC.

That's exactly what happened to a 20,000-square-foot mansion on North Hillcrest Road in Beverly Hills, which was originally listed in 2018 for $100 million and included a gold-painted Lamborghini and Bentley.

This L.A. mansion comes with a gold-plated Lamborghini

The mega-home is still for sale and recently had a $32 million price reduction; it's now listed with Williams & Williams Estates Group for $68 million, but those gold-painted rides are no longer included.

CNBC's Ray Parisi is the senior executive producer of special projects.

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