There were young mullets, ranga mullets, luxurious mullets and curly mullets, the participants bonded by the common credo of "business at the front, party at the back".

Summernats co-owner Andy Lopez couldn't have been more delighted at the turnout for inaugural mullet gathering, celebrating a hairstyle which emerged in the 1970s and has somehow survived the vagarities of follicle fashion ever since.

Rarely does a common hairstyle bond a group of strangers but out in the blazing sun of the main arena of Exhibition Park, there were handshakes all round and friendly banter between rival mullet-wearers.

Andy Lopez described the mullet as embracing all the fun elements of Canberra's annual Summernats street machine festival. Throughout the event he has been regularly donning a blond-tipped mullet wig for media interviews and photo opportunities, declaring himself somewhat envious of those with enough self-belief to carry one off all the time.

"A mullet might suggest that you're not willing to take yourself too seriously but that being said, there are some pretty serious mullets here," he said.

"This is the first time we've done this [competition] and I'm pretty sure it's going to be a permanent fixture from here on".

As the mercury climbed into the mid-30s and a fierce westerly wind whipped through the site of Australia's largest street machine festival, the limited coolness of the main judging pavilion attracted thousands of onlookers.

The main pavilion was reserved for the top 60 vehicle entries of the show, among them two outstanding entries from Canberra's Camilleri brothers, Adam and Jake.

The brothers share a love of cars, but of very different styles. Displayed alongside each other were Jake's highly customised 1932 Ford Tudor hotrod and Adam's completely original 1968 HK Monaro GTS coupe.

Adam, a chef by trade who now lives in the Sydney suburb of Concord, returned his award-winning Monaro to Summernats this year after a two-year absence.

Despite having 190,000 miles on its odometer, his Monaro looks - and drives - like it had when it rolled out of the Holden factory in Dandenong 50 years ago.

The car has been meticulously rebuilt from the wheels up with attention given to every single nut and bolt. If it wasn't completely original, it was rejected.

Adam's immaculate yellow Monaro is insured for $175,000 but given the thoroughness of its restoration and its hugely collectible Australian "muscle car" status, would likely fetch two or three times that at a specialist auction.

Obtaining factory-original parts in perfect condition for a restoration such as this, he said, is getting progressively more difficult.

"You have to search pretty hard; I had to drive to Broken Hill to buy a rubber seal kit," he said.

The Monaro is rarely driven, and never in the rain.

"But you have to drive it every so often because even rare and valuable cars like this are dynamic things; they are made to be driven."

When the Monaro is taken for a drive, it attracts more attention than a exotic supercar.

"We usually don't stay parked anywhere for too long because a crowd starts to gather around it pretty quickly."

Show car co-ordinator Owen Webb has been in the Summernats judging pavilion for every single event since it began in Canberra 32 years ago. He started as an entrant, became a paint judge for 10 years, then was chief steward for 20 years. For the past two years he has co-ordinated the unveiling of the show cars.

This year's array of show cars, he said, is quite special.

"What a lot of people don't realise is that because it takes five years or more for a really high quality car to progress through its build to its completion, this results in cycles where you get a whole lot of high quality cars emerging at once," he said.

"This year is one of those rare years where we are at the top of the build cycle and all these really amazing, high quality cars are here, so whoever wins will really deserve it."

An ACT Policing spokesman said police had been "generally satisfied" with crowd behaviour at Summernats.

"Police would like to remind attendees to drink responsibly, be respectful of others and obey applicable road rules."

An Emergency Services Agency spokeswoman said a 20-year-old man had been taken to hospital on Saturday afternoon after becoming dehydrated at the festival.