America may have glamorous socialites and reality-show celebutantes like Paris Hilton and Kim Kardashian, but when it comes to seriously conspicuous spending, it’s hard to top Britain’s Ecclestone sisters.

Especially when it comes to real estate.

The Ecclestone heirs, Petra Stunt, 24, and Tamara Ecclestone, 28, have spent well over $200 million between them on homes — and home makeovers — in London and Los Angeles. And their spending sprees seem to have fuel to burn.

Their father, Bernie Ecclestone, the 82-year-old billionaire owner of Formula One racing, set aside $4.5 billion in Bambino Holdings, a trust fund primarily intended to be used by his ex-wife, Slavica Rasic, and daughters for real estate investments.

But are these extravagant homes and renovations what Mr. Ecclestone had in mind?

Mrs. Stunt, the younger sister, made waves on this side of the Atlantic two years ago when she bought the late television producer Aaron Spelling’s “Manor” in Holmby Hills for $85 million — still the highest price ever paid for a home in Los Angeles County. She then spent close to $20 million renovating the 57,000-square-foot home, a project that involved some 500 workers who toiled around the clock, according to brokers involved in the sale. What was the rush? She had only three months to get the job done before her wedding to the British entrepreneur James Stunt.

Mrs. Stunt also reportedly owns a town house in the Chelsea neighborhood of London that she bought in 2010 for about $90 million.

Not to be outdone, her sister in 2011 ordered the opulent renovation of the London home on Kensington Palace Gardens, the most expensive street in the country, that she had bought for $70 million. The plans, whose price tag The Daily Mail put at about $27 million, called for a bowling alley, a hair salon and a dog spa.

Lately Ms. Ecclestone has been renting a home in Bel-Air (not far from her sister’s mansion) for $150,000 a month while she house-hunts in Los Angeles. Her search has taken her to Fleur de Lys, a $125 million listing in Holmby Hills modeled after a French palace. More recently she toured a home nearby built on the site of the former Walt Disney estate, now owned by Gabriel Brener, the scion of a Mexican industrialist, who is asking $85 million for his 35,000-square-foot home, once the site of a one-eighth-scale train that Disney used to give neighbors rides on.

Is this a case of sibling rivalry? The British tabloids and some Los Angeles brokers have speculated as much. A better question might be whether Ms. Ecclestone is a real buyer, or is just looking for attention.

The British media have generally portrayed the sisters as spoiled publicity hounds, and have quoted their father criticizing the way they were spending their trust funds. He was none too pleased in 2011 when his elder daughter did a three-part British reality show called “Billion $$ Girl,” which chronicled her lavish lifestyle. That same year she posed naked on her bed fondling £1 million in cash for the photographer Tyler Shields. (Efforts to reach the Ecclestone sisters through business representatives were unsuccessful.)

Perhaps a little too serendipitously, TMZ reporters have been able to interview Ms. Ecclestone as she has been spotted leaving a few majestic estates around Los Angeles.

One broker familiar with her search said Ms. Ecclestone thought the Brener home was too small. “She liked the grounds but found the house not grand enough,” said the broker, who declined to be identified, citing client confidentiality.

She also toured the 24,000-square-foot compound that the “American Idol” host Ryan Seacrest bought from the comedian Ellen DeGeneres last year for $37 million. “It was different,” she told TMZ

Brokers in Los Angeles are itching for someone — a billionaire heiress would do nicely — to break the $100 million barrier on a home sale. Two homes in the San Francisco Bay Area have sold for $100 million or more, the most recent being a house in Silicon Valley that sold for $117.5 million, reportedly to a Japanese billionaire.

It’s not as if owners in Los Angeles weren’t trying, though. Some of the best estates in the Bel Air/Beverly Hills/Holmby Hills triangle, where most of the priciest homes are, have been listed above $100 million, including Fleur de Lys, the Beverly House ($115 million) and the financier Gary Winnick’s eight-acre spread in Bel-Air, which he wants to sell for $225 million, brokers said.