Miraculously, the driver of the next car was an anesthesiologist. He started Matt breathing again, keeping him alive until a helicopter came.
Matt's face was rebuilt and his brain recovered, an odyssey chronicled in The Inquirer.
But the moment Matt walked out of the hospital after 25 days, he knew that for him, the symbol of his full recovery would be to complete an Ironman Triathlon - in his mind the ultimate test of athletic endurance.
Matt's parents and girlfriend were uneasy with this idea. He was in medical school now, at the University of Pennsylvania. What better symbol of recovery than that?
Matt was nothing if not determined. Determination and drive were the reasons he had recovered as well as he had, and now, the Sunday after Thanksgiving, his test had arrived.
The race would begin at dawn, and at his best he wouldn't finish until after sunset.
Matt did not expect to win. He was just hoping to finish safe and strong. There were so many things to worry about. Would his bike break down? Would his body break down? The high humidity and Caribbean sun would make a mid-80s day feel in the 90s. And the special helmet he wore biking - to cover his reconstructed face and jaw - would make a hot ride hotter.
To calm himself the evening before, and for perspective, Matt read through e-mails he'd received after the first stories about him were published.
"People said that I inspired them," Matt said. "Well, they inspired me right back. One of them had a quote from Winston Churchill, which I think is perfect for a triathlon:
" 'Success is not final; failure is not fatal. It is the courage to continue that counts.' "
Back on Oct. 10, Matt did a sprint triathlon at the Jersey Shore as a warm-up to Cozumel. It was a baby by Ironman standards: quarter-mile swim, 10-mile ride, 3.1-mile run.
He finished in just under 55 minutes. A good day.
Driving back to Philadelphia, Matt explained why the Ironman was so important to him. He said he loved the beauty and balance of triathlons, the combination of three forms of exertion. He also loved challenges, and this was the ultimate.
When he was at the University of Virginia hospital, every bone in his face broken, his carotid artery about to rupture and needing a stent, his jaw wired shut, a tube in his throat, Matt believed he'd one day be back to running and biking and swimming, and he set no less of a goal for himself than to complete an Ironman.
Matt had trained hard all last summer but had cut back to 15 hours a week in medical school, usually getting up at 5 a.m. His attitude about Mexico, he said, was 50 percent to compete at his best, and 50 percent just to complete the race, to accomplish his goal.
During that car ride home, Matt also talked about Fran Crippen, a legend in Philadelphia and University of Virginia swimming circles. "I'm sure he'll represent the U.S.A. in the 2012 Olympics," Matt said.
Matt, who swam for UVa for a year before falling in love with triathlons, had met Crippen only once or twice. But Matt's older brother, Michael, had followed Crippen as team captain.
In the car that day, Matt told this story: At the conference swim meet every year, Virginia swimmers paint a big V on their chests.
But in 2006, with Virginia in a battle for first place, swimmers painted a smaller F and C on either side of the V.
This had never happened before, or since. But Crippen was so beloved, so admired, that the swimmers did this to honor their captain in his last college race.
Thirteen days after that car ride, on Oct. 23, Fran Crippen died off the coast of Dubai in a six-mile swim in 86-degree water. The water was simply too hot. Others were hospitalized and said no safety boats were nearby when they needed help. Fran's body was found two hours after the race.
Matt wept openly as did a thousand others at Crippen's funeral. "So much could have been done to prevent that from happening, and I hope to heck it changes," Matt said.
His heart went out to the Crippen family, and also to Mark Bernardino, the Virginia swim coach, who spoke at the funeral.
Mark Bernardino had come to the UVa hospital every day after Matt's accident. He had pushed Matt to get better and walked with him in the hallways and up and down the stairwells. It upset Matt deeply to see Bernardino now feeling such grief.
Learning of Crippen's death, Emily Privette, Matt's girlfriend, shocked and upset, told him:
"You can't do the Ironman."
Emily, who graduated with Matt from UVa and was now a medical student with him at Penn, had spent nights in a chair at his bedside after his accident. If this happened to Fran, she feared, it could happen to Matt.
After the funeral, Matt acknowledged, "I am more nervous now." He wasn't going to let Emily change his mind, but he did re-evaluate his goals for the triathlon.
"I'm going to be very hypersensitive to my body in Cozumel. After what happened to Fran -
"Now I'm pretty much at 100 percent just wanting to finish and finish strong."
He began to work much harder at heat acclimating. When he ran on the treadmill at 5 a.m., he'd turn up the thermostat full blast, and wear Underarmors, hat and gloves. On the indoor bike trainer, he'd wear layers and his full-face helmet.
Matt had a long talk with Bernardino the week before Cozumel. Bernardino wanted Matt to be beyond cautious, and tried to convince Matt that during the biking and the run he should repeatedly take his temperature, to make sure he wasn't overheating.
Matt, the first-year medical student, explained that the only way to get a reliable reading was with a rectal thermometer, and that just wasn't going to happen. He would be careful. He promised.
By 5:30 a.m., before dawn, Matt was checking his bike, filling water bottles, stuffing protein bars in nooks and crannies.
At 6:25, he found his family and said goodbye.
"OK, gorgeous," said his mother, Nancy, hugging him.
His father kissed Matt on the top of his crew cut - another attempt by Matt to keep cool - and gestured "I love you" in sign language. Matt started doing this when his jaw was wired shut.
His brother Michael, a law student at Stanford, zipped up Matt's triathlon suit in the back, the finishing touch, like a husband zipping his wife's dress before a night out.
Hidden underneath were the letters Michael had drawn on Matt's chest that morning. A big V, with a smaller F and C on each side. Matt had asked Bernardino if it would be OK.
Standing with 2,300 other swimmers on the dock, as the Ironman was about to begin, Matt was thinking, "how incredible it is, how blessed I am just to be able to start this race. Two years ago exactly I was leaving the hospital."
At 7 a.m., the horn sounded and he was off, lost in a crush of orange swim caps in a turquoise sea.
To avoid being kicked or clobbered, Matt's strategy was to start near the front - swimming was his strongest leg - and get ahead of the mayhem, settle into a smooth stroke, and relax.
A man had drowned during the Philadelphia Sprint Triathlon last summer, with far fewer swimmers in the water.
Matt quickly found a pack of good swimmers and settled in behind them.
Less than an hour later, the Millers, on the beach, saw Matt emerge from the water. They could see he was among the leaders, but just how well he had done was quickly confirmed by an e-mail Matt's father, Mike Miller, received on his BlackBerry:
"A 52:36 swim! What a start! Looks as if he was first in his age group out of the water. And 44th overall. Incredible!"
The e-mail came from Chris McIsaac, who works with Mike Miller, a managing director at Vanguard in Malvern, and was watching live streaming of the race online.
Emily was following online as well. As much as she had wanted to make the trip, Emily had felt it important to spend Thanksgiving with her ailing grandmother and family in North Carolina and posted on Facebook at 9 a.m.: "Emily Privette is SO excited for Matt Miller who is doing his FIRST IRONMAN RIGHT NOW!!
Mounting his bike, Matt expected the 112 miles to take him at least six hours. His strategy was to start out slow, to ride the second half faster than the first. A veteran had told him, "It's going to be a race of patience," and he kept repeating that to himself.
Nearly four hours into the bike leg, at 11:45, the Millers spotted Matt at the 75-mile mark. They screamed, but Matt didn't acknowledge them.
"I don't think he saw us," said his mother.
"But he definitely heard us," said his father.
"The main thing I was thinking about was hydration," Matt said later.
The streets were crowded with people cheering. "I felt like it was the Tour de France," Matt said.
Riders repeatedly passed the rider with the strange helmet on the first two laps around the island, but Matt was doing the passing on the final lap, startling one rider who later blogged, "I said out loud, 'WTF?' "
As the Millers saw Matt dismount, an e-mail came in: 5 hours, 37 minutes, 44 seconds.
He'd averaged 19.9 miles per hour.
Matt disappeared into the transition tent where he drank, and drank some more. "I'll see you in a few hours," he said as he trotted off to now run 26.2 miles.
This part also worried Matt's family. Matt had finished a marathon in Virginia Beach last March, but he became dangerously dehydrated and spent 90 minutes in the medical tent.
"I was ghostly white, with an elevated heart rate well over half an hour after I had finished," Matt recalled. "My father told them I was planning to do an Ironman Triathlon. The cardiologist in the tent working on me said, 'You can't do that. I know what first-year medical school is like.'
"I got over that pretty quickly," Matt said. "My family didn't."
Matt had decided that in Cozumel he would slow to a walk for 30 to 90 seconds at every water stop - every kilometer - to eat, drink and dump ice down his shirt, down his pants, on his head.
"Mile 14 to Mile 21 was the toughest part," he said later. "I just kept making myself run to every aid station, where I could eat and drink and walk. That was my goal."
As the shadows lengthened that afternoon, so did Matt's perspective.
For the whole race, he had focused on his body, his bike, on taking care of himself. Even at dusk, with his sunglasses still on, he was being very careful with every step in the growing darkness.
But a mile from the finish, he grew emotional. He started thinking about his longer journey - how far he'd come, what he was about to accomplish, and the doctors, friends and family who had healed him, cheered him, and helped him get here.
More than 50 faces, maybe 100, flashed through his brain like a slide show.
"I think the first thought that came to me was 'Wow, Matt, you left the hospital two years and two days ago, and now you're almost done an Ironman Triathlon, faster than you and a lot of other people ever thought you would go."
As he turned the corner for the last 40 yards, he saw his screaming parents and then his image on the giant screen above the finish line.
As he took those last few strides, Matt heard the announcer proclaim, as he did for every finisher, "Matthew Miller of the United States, you are an IRONMAN!"
Matt crossed the line and stopped. He stood tall, arms stretched out, face skyward, and surrendered himself to the moment. He was happy, proud, grateful - and so glad it was over.
"We did it," he told himself. "We did it."
His time was 10 hours, 30 minutes, 12 seconds - 209th overall.
His marathon was 3:42:26.
He threw his arms around his parents in a three-way hug.
He got his cell phone and called Emily. "I can't talk long," he said, "I'm pretty tired." Then he called Bernardino. "You're talking to an Ironman."
"Will you ever do another one?" his father asked.
"Maybe in like 10 years," he said.
After the race, Matt pulled down the shoulder straps of his triathlon suit. On his chest, nearly rubbed away now, was the V, with the smaller F and C on each side.
Matt spent Monday recovering in Cozumel, and Tuesday was a marathon of its own, of security checks and a missed connection, and he didn't get into bed back in Philadelphia until after 2 a.m.
Yet still, on a rainy, miserable Wednesday morning, he was seated in an auditorium by 8 a.m., just another medical student in just another anatomy lecture.
"Grace and Grit," the story of Matt Miller's accident and recovery, is at
A video of him competing in the Cozumel Ironman is at www.philly.com/seeMatt
Contact staff writer Mike Vitez at 215-854-5639 or firstname.lastname@example.org.