Australia's largest car festival has roared to a close in Canberra, ending its 38th year with celebrations and a brawl that police had to contain.

The four-day event drew about 130,000 people and a record 3,000 entrants to its show car and stunt demonstrations amid challenging heat and windy conditions.

Adam Bickerstaff was named Summernats Grand Champion after he raced his 1956 Ford F-100. (ABC News: Callum Flinn)

Adam Bickerstaff was named Summernats Grand Champion for racing his 1956 Ford F-100, while Chris Orchard won the Pro Burnout Series, taking home $50,000.

Mr Bickerstaff described his Grand Champion win as "unbelievable" and "surreal".

"I cannot believe that we've come this far. We've made it. To win the sword is just next level. We never thought it'd happen,"

he said.

Chris Orchard won the Pro Burnout Series, taking home $50,000. (ABC News: Callum Flinn)

Police contain brawl

A fight in the Burnout Stand on Saturday sparked a police response at Summernats, raising ongoing concerns about antisocial behaviour.

ACT Policing said an investigation was underway after officers attended the incident to support security guards.

Police warned attendees to expect an increased police presence at venues and on roads. (ABC News: Callum Flinn)

Summernats managing director Andy Lopez said the altercation had begun as a disagreement between spectators.

"It was contained reasonably quickly,"

Mr Lopez said.

"As per our protocols, there was a security and police response to diffuse the incident and a number of patrons were ejected."

Police had warned attendees ahead of the event to expect an increased police presence at venues and on roads. By the first day, police had already seized four cars for alleged illegal driving.

Expansion across the ditch

Organisers declared the festival a success despite extreme weather, with temperatures in Canberra at times soaring above 35 degrees throughout the four days.

Andy Lopez says Summernats will debut in Hamilton, New Zealand in 2027. (ABC News: Adam Kennedy)

Saturday night's fireworks display was cancelled due to the ACT's total fire ban, the territory's first in six years.

"We made a lot of changes on the fly to deal with the weather that was coming,"

Mr Lopez said.

Despite the challenging conditions, Mr Lopez used the festival's final days to announce plans to expand Summernats to New Zealand, with its first event scheduled for 2027.

"We have announced Summernats's second international event. So we're in the USA in March, and we're going to be in Hamilton at Mystery Creek," Mr Lopez said.

"It's a 10-year dream that's coming true and we're really excited."

Mullet champion named

Wild weather forced Saturday's MulletFest heat indoors, where children and adults competed for the best mullet and a place in the national grand final in Kurri Kurri, NSW, in December.

Migelly Shaw (right) won the Grand Champion title in Summernats's MulletFest. (ABC News: Callum Flinn)

Adult Grand Champion Migelly Shaw said the competition was "always a lot of fun" and "a real great show".

Mr Shaw grew out his previously clean-shaven look three years ago, getting a mullet for his younger brother's wedding, and has not shaved it off since.

"I let it be its thing. I did get a perm recently. So it's a bit wavy, cut some length off it, and now I just rock it."

'Somewhere to express our hobby'

Adam Povey from Cooma entered his Peel P-50, a three-wheeled micro-car recognised as one of the world's smallest production cars.

Adam Povey has attended Summernats for 28 years. (ABC News: James Vyver)

"I was actually very nervous about bringing it. I bought it for the first time last year. It's been loved," Mr Povey said.

"The P-50 is very different to all the cars that you see here. It's unique, it's cool. Grown men love it, grown women love it and the kids absolutely adore it."

The car enthusiast, who has attended Summernats for 28 years, said he kept returning for the atmosphere and to catch up with friends.

"It's somewhere for us to express our hobby and share it with everyone."