Summernats 2018: City Cruise | photos

The grass roots social media campaign that persuaded the ACT government to reverse a ban on cars in Braddon over the main nights of Summernats had come as a pleasant surprise, event co-owner Andy Lopez says.

Mr Lopez, who was in Civic for Thursday's City Cruise, said the surge of community and business support for street legal cars to circulate in the centre of Canberra indicated people had taken the event to their hearts.

While not as big as last year's 30th anniversary Summernats, 2018's celebration of burning rubber, V8 engines and high octane fuel is expected to be the second largest ever.

Mr Lopez, who described the City Cruise as Summernat's opening ceremony, said between 25,000 and 30,000 people had been expected to watch the 300 cars taking part on Thursday.

"The city cruise represents what Summernats does for Canberra," he said. "It brings life, colour and movement. Summernats will bring about $25 million into the city in January. It also keeps young people in jobs over the summer which is fantastic."