It only takes about five hours for skilled hands to strip a vehicle in preparation for a figure 8 race, in which light and maneuverable compact cars zig-zag across each others’ paths as they surge towards the final lap in a frenetic series of collisions, sideswipes, spin outs and crashes.

Beneath the bleachers where an enthralled audience applauds each new disaster, a long table is covered with paper plates of carefully arranged vegetables grown by Marshfield locals and the perimeter is surrounded by oversized, prizewinning gourds.

A few steps away, 50s music seeps from a stage surrounded by baby boomers, and around the corner children line up for pony rides.

And thirty miles north from this pastoral flashback is downtown Boston.

“The Marshfield Fair is a way to promote agriculture,” says Marshfield farmer Carleton Chandler, who’s helped manage the fair for decades, together with Marshfield Agricultural Society president Lenny LaForest.

“But you have to attract the people here with something. They’re not going to come to see a plate of tomatoes.”

The fair has grown considerably since its 1867 birth and continues to add new features and attractions. When Suffolk County law forbid the continuation of thoroughbred horse racing in 1991, motor sports were a natural fit for the gap at the fairgrounds racetrack.

Since then, the demolition derby, often called “demo,” has been a consistent draw. Rather than add complexity to an already sprawling event, the fair contracts JM Productions, longtime derby promoter from New York, to handle the motorized mayhem.

Compact cars are attractive for several reasons: There is a ready supply of junked cars, the stripping process is quick, and front wheel drive allows for plenty of damage to the tail end before the cars give up the ghost. As a result, the compact-car figure 8 is increasingly popular.

Compact cars can’t endure as much of a beating as a full-sized American sedan from the 1970s, like the iconic Chrysler Imperial, but at least one of the cars at Marshfield’s final figure 8 had managed seven performances in two days.

Marshfield actually fields a double figure 8, with an extra loop tacked on to the end. The track itself is framed by concrete barriers. Cars slalom between three impossibly large farm equipment tires, each as wide as a car is tall, which work with the chewed-up mud track to keep average speeds below 15 mph.

Six cars at a time race in a heat, with the winner continuing to the feature event. Excitement kicks in the moment the cars pass the first tire. Young children and bored slackers tune in hopes of seeing accidents. The demolition derby provides that, but in a safe context and with a lot more action.

A few laps in, bumpers litter the racetrack. One car’s mismatched tires churn the mud into soup as the wheels bend and come off. The driver refuses to concede, forging ahead on bare metal in a shower of sparks.

“It sure smells better than the rodeo,” quipped an audience member. Moments later car #1, “American Dad,” erupts in white smoke, filling arena and grandstand with the eye-stinging scent of overheating engine.

“I guess I was wrong. The rodeo didn’t smell so bad after all.”

After the final figure 8 race, the evening ends with a joyous old-school demolition derby in which the winner is the last car able to move.

Jay Milligan gives an opening lecture to the drivers in the pit: “Try not to hit anyone. We expect to see contact but you don’t win by slamming into people. No wheel jerking. You race for yourself.”

Milligan works for JM Productions, founded by his father, and makes it clear that hitting a driver-side door will get you ejected immediately. “Don’t worry about what’s behind you, just look out in front of you. Don’t stop ’til the race is over. Even if you’re in last place on lap 7, you can still win.”

In spite of low speeds and safety measures, this is a dangerous sport. Each participant has paid an entry fee which covers administration costs and provides rudimentary insurance coverage in case of catastrophe. All drivers must cut a hole in the hood of their car so on-hand firemen can easily insert a hose when an engine fire breaks out.

A strong air of camaraderie floats over the pit area before the race, for familiar faces abound, and many of the drivers have long histories together. They readily swap jokes and jabs as well as tools as they tweak their cars and repair damage from earlier races. Anything that isn’t essential to powering and controlling the vehicle must go: seats, glass, wiring, heating, even the dashboard.

All this has been done hours before the show, but junkers are not always reliable. “It’s a sport where you’re working with old cars, so something always breaks on ’em. It’s not like you got a brand new car and everything always works,” says Steve Zimmerman, who runs Shoe City Auto Sales in Brockton.

“Most of the people in this, their wife or their girlfriends are involved too,” says Zimmerman, when asked about the possible relationship hazards in demolition derby driving.

“A husband and wife team,” Zimmerman says, pointing out Gary, dubbed “Chief Wahoo” by fellow drivers. His wife, “Jayhoo,” helps put the cars in order, but doesn’t drive. “It’s too much work just to get him in and out of there,” she says.

“We see a lot of competition from area garages, a lot of times they’ll try to raise money for charities,” says Chandler, of the derby participants. “It becomes kind of a grudge thing.” This is apparent in the efforts of another driver to deflate Gary’s ego by painting his own car with the word, “Wa-who??”

A demolition derby is not a moneymaking enterprise. According to Zimmerman, the $150 prize for winning a heat “doesn’t pay for the fuel.” Drivers procure their doomed chariots “Wherever [they] can find them.”

Some say the draw is adrenaline, some say it’s the challenge of engineering a car and racing it. “It’s bragging rights for them, basically,” says Jayhoo.

“They want to win,” Zimmerman adds. “Some people go out there trying to win, others just go out to try and wreck a car. It all depends on what you want to do, what your strategy is.”

The heft of his father’s 1st place heat trophy takes some of the sting out of his Chris Woodworth’s own 5th place finish.

“My car stalled out several times,” he mutters. His girlfriend, Jennifer Cass, beams with excitement anyway; she came in 3rd in last night’s demo, her second.

“I got into it through him,” she says, waving to Chris. “I love it. But if he doesn’t win, sometimes he won’t even talk on the ride home.”

“Fat Belly” John Kelly of Dedham, 26, of Dedham, won the 4th heat in an exciting finish. His wife, Jennifer Mann, placed 2nd in, taking home $500. Kelly’s well-earned trophy is as large as his daughter, who’s the same age John was when he saw his first demolition derby.

“I knew I wanted to do this ever since I was four. I couldn’t wait to turn 18 just so I could drive in the derby.”