Chic Henry, who ran the annual car show for its first 22 years, said he was disappointed Summernats 26 had not been promoted as a Centenary of Canberra event after being one of the city's largest annual drawcards for a quarter of a century.

Mr Henry said Summernats had battled for decades against snobbery and being regarded as ''stupidity'' by elements of the Canberra establishment.

But a centenary spokesman denied on Friday the event had been excluded from official 100th birthday festivities, saying the organisers had been free to market the show as a centenary event.

An official Centenary of Canberra event called Spin will be held in October but will not be solely focused on motoring.

The Summernats promoters, Out There Productions, tendered unsuccessfully to stage the Spin event but Centenary of Canberra spokesman Jeremy Lasek denied car enthusiasts had been frozen out of the official 100-year celebrations.

''Summernats is an iconic Canberra event, hugely supported by Canberrans and tens of thousands from outside of Canberra and we are thrilled that it is setting off the centenary year in such a fine spirit,'' Mr Lasek said.

But Mr Henry, who said he was not speaking on behalf of the Summernats management team, said this year's show had been snubbed as it was not promoted as an official centenary event.

''It could be [snobbery], because that's a thing that I've encountered for years and years in the ACT and I know we've been left off lists by tourism and the like,'' he said. ''It's an enormous shame that an event that is so significant to a lot of people in the ACT gets treated with disregard. I think it's bloody terrible.

''Just because we don't fit the mould of what people think Canberra should represent, there would be more opportunity for the international stringed ensemble to take centre stage.''

Mr Henry said former chief minister Jon Stanhope had wanted a Summernats flavour to at least one official centenary event but the creative director, Robyn Archer, had not followed up on it.