Aug. 31, 2009 -- The Mercedes 600 carrying Princess Diana and her companion Dodi Fayed was traveling more than 85 miles per hour when it hit a concrete pillar head-on in the Place D'Alma underpass, crumbling like an accordion.

Both were killed, as well as the driver, Henri Paul -- later proven to have been under the influence of alcohol.

The Paris accident -- just before 12:30 a.m. local time 12 years ago today -- ended the life of one of Britain's most celebrated royals, unleashing a torrent of emotion in that historically stoic culture and catapulting Diana to near sainthood status.

In the days that followed, she was memorialized as the "People's Princess," as those devastated by her loss turned on the nation's out-of-touch monarchy, whom they blamed for her tragedy.

Conspiracy theories, all unsubstantiated, abounded. Had she been assassinated by the royal family so her estranged husband, Prince Charles, could marry his longtime love Camilla Parker-Bowles? Did the British Secret Intelligence Service bump her off because she was pregnant with Egyptian Fayed's Muslim child?

But the most baffling question was whether doctors could have done more to prevent Diana, 36, from dying.

The horrific accident illustrated the difference between the French and U.S. approaches to emergency care -- a relatively small piece of the French medical system, but deemed by some people to be the best in the world and often cited as a model for U.S. health care overhaul.

When rescue workers arrived, Diana was conscious, uttering, "My God" and "Leave me alone" to the swarming paparazzi. Although she had suffered internal injuries, she did not arrive at the Parisian hospital for 110 minutes -- too late for the surgery that some speculated could have saved her life.

Diana's last hour -- in cardiac arrest and bleeding to death -- was spent in a mobile medical unit parked a few hundred yards from Pitié-Salpêtrière Hospital, where an emergency team followed French protocol and administered treatment at the scene of the accident and en route to the hospital.

At the time, many people surmised that had a U.S. ambulance responded, Diana would have been rushed to the nearest emergency room, where a full set of professionals and diagnostic equipment might have revived her.

Colloquially known as "scoop and run," the U.S. system is grounded in studies that show a trauma victim's best chance for survival is reaching the operating room within 10 minutes.

Under the French system, "stay and play," a fully equipped medical ambulance with a doctor stabilizes the patient and then directs him or her to a specialized hospital, even if it is miles away.

Car Crash Victims Served 24/7

"When a patient rolls into the American system, they have a level-one trauma center that runs 24/7, with every specialty and myriad resources for a patient in a car crash," said Dr. Preeti Jois-Bilowich, emergency room doctor at the University of Florida's Shands Hospital.

Two or three paramedics focus on the ABCs of first responder care: airway, breathing and circulation. Each state has different licensing requirements for its emergency workers and ambulance services.

In France, the government-run Service d'Aide Médicale d'Urgence (SAMU), or Emergency Medical Assistance Service, provides more uniform care, coordinating the mobile resuscitation units. Teams always include one doctor, usually an anesthesiologist or emergency room physician, and a driver who serves as a technician and a nurse paramedic.

In Diana's case, a doctor who was passing by was the first on the scene and called for the ambulance, which arrived in seven minutes. He saw no visible injuries and treated her for shock with oxygen.

Fayed and Paul both died at the scene and were taken directly to the mortuary.

The SAMU team spent an hour treating her in the tunnel. Then, following French emergency standards aimed at not further injuring the victim, they drove slowly to the hospital about 4 miles away.

Yards from the hospital, her blood pressure dropped and the ambulance stopped again to revive her.

Diana Delayed 110 Minutes Before Death

Diana didn't arrive until after 2 a.m. -- 1 hour and 45 minutes after the crash -- and underwent an emergency thoracotomy. Coroners pronounced her dead from hemorrhaging that resulted from major chest trauma and deceleration that caused a rupture of the left pulmonary vein.

Later, surgeons said that her heart had been displaced from the left to the right side of her chest.

In the 1998 book, "Death of a Princess," Time magazine reporters Thomas Sancton and Scott MacLeod were critical of the French system, arguing that Diana could have been saved in a hospital operating room. SAMU was so upset with the indictment, according to the authors, that they threatened to sue.

But Sancton and MacLeod later rescinded their theory, based on evaluations of the medical records, in a 2004 Vanity Fair piece on the British inquest into Diana's death.

"I have actually revised my conclusions based on a fascinating series of interviews with a trauma specialist in Houston," Sancton wrote in an e-mail to ABCNews.com. "The bottom line is, whatever the merits or demerits of the French emergency medical system, poor Diana was a goner from the beginning because of the particular nature of her deceleration injury."

Defenders of the French system say that major road accidents like Diana's represent only about 12 percent of all emergency calls. Most are falls, domestic accidents, cardiac arrests and neurological problems.

And even Jois-Bilowich of the University of Florida, who did her medical internship with SAMU in Paris in 2006, sees its advantages.

French Emergency Workers Treat and Leave

"A lot of time, you get to the scene and you realize you can treat the patient right there," she said. "You can reassess in about 20 minutes and probably leave. Somebody who has diabetes in the morning and didn't eat and had a hypoglycemic episode -- their sugar comes up and is good and you leave.

"Here, they get transported to the emergency department and adds one more patient to an already overburdened emergency room.

"In France, you have physicians available and you treat it right there," she said. "You take the drug bag to the scene, it has just about anything you can imagine. It's a mini-crash cart. It's kind of like a mobile emergency department, with limitations."

But those limitations can be significant without X-ray or sonogram capability onboard. Jois-Bilowich recalled one Paris call during her internship in which a man collapsed at an apartment construction site.

The team set up a mini-emergency room and, for 45 minutes, ran an EKG, did CPR and began medication for a heart attack.

Without full emergency room diagnostics, doctors had to make an educated guess on the drugs. They were right, he survived but, had he ruptured an aorta, the drugs could have caused more problems or death. "You make judgment calls," Jois-Bilowich said.

The French emergency care reflects the overall health attitudes of that nation -- delivering basic primary care and health education to everyone will mean fewer expensive emergency room visits and hospitalizations later on.

Amid the health care debate here, some Americans are taking notice.

The French, at 10.7 percent of the gross domestic product, spend less than Americans do on health care at 16 percent of their GDP, according to 2009 Organization for Economic Cooperation and Development health data.

French Health Care Tops World

The World Health Organization recently rated the French system as the best in the world. By comparison, the United States rated 37th. The average life expectancy in France is 79.4 years, two years fewer than in the United States.

Both countries are struggling with rising drug costs, aging populations and unemployment, but about 65 percent of all French citizens, compared with 40 percent of all Americans, are happy with their medical care, according to the Organization for Economic Cooperation and Development.

The French can choose their own doctors, see specialists and have access to some of the most sophisticated research and medical technology in the world, according to Victor Rodwin, professor of health policy and management at New York University.

"The American and French system share similar dimensions," he told ABCNews.com. "They are both based on fee-for-service practices, there is a large element of private provision and they also have a small equivalent of the gap supplement insurance like Medicare. It's a public-private mix."

In France, everyone is covered, regardless of their ability to pay, with an emphasis on primary care to prevent long-term illness.

"What we do is quite different," Rodwin said. "We take care of people, but not everyone, and we do it once they get very sick. We take diabetics with flare-ups and asthmatics in the emergency room, but we don't do primary care or health education as well for the poor.

"Our population is much sicker compared to France," according to Rodwin, whose research finds that Americans have the highest rates of avoidable hospitalizations -- two and a half times higher than the French -- for treatable conditions like pneumonia, asthma, diabetes and congestive heart failure.

That's according to a 2008 study from the National Institute of Public Health and the Environment. "The French have a term -- solidarity," Rodwin said. "Since World War II, the system is grounded in the philosophy that everyone should have access to health care. That doesn't mean everyone is treated equally. There are those who are more educated or higher socio-economic groups that use more specialty care and probably have access to better quality care, but everyone has access to the minimum."

Mary, a freelance writer who did not want to use her last name, lives in Paris and is a "big booster of the French system."

The school nurse called the fire department after her son had an asthma attack several years ago.

"Soon after, I received a call from a doctor on the scene telling me exactly what was going on and what treatment Luke was getting at the school," she said. "He suggested taking Luke to the hospital for a few hours of observation, after which I could pick him up."

U.S. Emergency Rooms 'Tangle of Forms'

"I find the emergency room responses the most dramatic change from the U.S.," Mary said. "I've always had excellent health insurance in the U.S. and I've found every American emergency room visit a tangle as I fill out form after form and sign over my first born before anyone will even look at an injured or sick kid.

"Here, because everyone is insured, there's never any questions in hospitals that people will be treated, and treated quickly, because there's no worry someone's going to be stiffed with the bill."

Jois-Bilowich agreed that the French system is more cost-effective and that most people admitted to U.S. emergency rooms are treated and then released. But, she argues, the U.S. system of trauma care is superior.

As for the ill-fated accident that took the life of Diana, she won't venture a guess at what her outcome might have been in the United States, noting that even simple trauma cases can "crash" on the operating table.

"I, personally, really hate the retroscope," she said. "We weren't there and we didn't know the circumstances. Every patient is an individual human being and not a computer system, and so many things can confound what you think is a simple situation."