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But Sancton and MacLeod later rescinded their theory, based on evaluations of the medical records, in a 2004 Vanity Fair piece on the British inquest into Diana's death.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