Buescher was in 11th place as he rounded the final turn and weaved his way through a massive pack of spinning race cars.
The accident, the third multi-car wreck in the waning laps, appeared to start as the tandem of Tony Stewart and Elliott Sadler charged to the top of the track to make a three-wide pack among the leaders.
Kurt Busch was leading on the bottom of the track with younger brother, Kyle, pushing, and Kurt Busch seemed to start sliding up the surface in an attempt to block the huge run on the outside. Joey Logano was being pushed through the middle by defending Daytona 500 winner Trevor Bayne, and all four cars began drifting higher into Stewart, winner of the last four Nationwide openers here, was pinched into the wall.
That triggered a chain-reaction crash that had many worried about the safety of the drivers involved.
"We got a big run on the outside, and all of a sudden the door got slammed on us,'' said Stewart, NASCAR's defending Sprint Cup champion. "I don't know why whoever it was turned right, but it wasn't a very good time to either try blocking or moving.''
Kurt Busch admitted he tried to "crowd the outside lane.''
"`Didn't know that there were two cars up there. I thought it was just a single lane,'' he said. "I was trying to side draft to get the best finish I could at the end. Everybody was racing to the end. Man, a lot of tore-up cars. That's just everybody full throttle at the end.''
There was initial concern for his younger brother, Kyle, who appeared to clear the wreck but was hooked by defending Nationwide champion Ricky Stenhouse Jr. The contact sent Kyle Busch straight into the wall.
"I don't even know where to start. I don't even know what happened,'' said Kyle Busch. "I thought we had the race won. Then those guys were coming on the top, and I thought, `We'll see where we settled in here.' When they all crashed up high, I was clear. I shot as low as I could, and somebody tagged me in the back and hooked me dead right. It was a really, really hard hit, and there were a few more after that. It seemed like they kept coming.
"I swore when they all went up high. I was the leader for a second, and I'm like, "I won this thing. I won this thing.'''
But it was Buescher, who went low - so low he crossed the yellow out-of-bounds line, but NASCAR said it's allowed when avoiding an accident - to skirt the cars and take the checkered flag. Buescher's win was his first in NASCAR and came a day after unknown John King won the Truck Series opener in another wreckfest.
The multiple big wrecks have prompted concerns about Sunday's season-opening Daytona 500. NASCAR worked hard during the offseason to break up the two-car tandem racing that fans disliked, and the return of pack racing has led to many accidents over SpeedWeeks.
But Brad Keselowski and Sadler, who finished second and third, both said they feel safe going into Sunday's race.
Keselowski said NASCAR is in a difficult position of giving fans what they want in restrictor-plate racing and making it a safe event.
"I feel like we walk a line in this sport between daredevils and chess players,'' he said. "When we come to Daytona and a track like this, we're maybe more on the daredevil side of the line. And then we go other places where I'd say we're more on the chess-player side of the line. I think it's important to have tracks like this that maybe average it back out a little bit.''
"Ideally, we'd like to just walk straight down the line all the time. But from a standpoint of the sport and the health of it, I think not a lot of people watch chess matches, and I've never seen one televised.''
Danica Patrick, meanwhile, started from the pole but was wrecked 49 laps into the race when JR Motorsports teammate Cole Whitt ran into the back of her while bump-drafting. Her car spun into the wall and back down the track. Although she returned the damaged Chevrolet to the track late, she finished 38th in the first race of what will be her first full season in the Nationwide Series.
"Well, we were just doing big pack racing and went down into three, got a little tap, got a little bit sideways, saved it, and then just got hit again and couldn't save it. You guys saw the rest from there,'' she said.