THE 20th annual Historic Leyburn Sprints are shaping as one of the biggest and best events yet, featuring a huge field of 230 cars spanning 100 years of motoring.

The time trials mark the 20th year since the community the event was started to commemorate the running of the 1949 Australian Grand Prix on the disused wartime airstrip.

Cars race one at a time against the clock in 55 classes covering sports, racing and touring cars. With seven runs per car across Saturday and Sunday, spectators will enjoy non-stop action.

Sprints Race Director Mike Collins said he was delighted by the packed program at this year's event, which was recently bolstered by a rare race car built and raced by Leyburn legend, the late Sir Jack Brabham.

"The Brabham is just part of an extraordinary line-up at Leyburn this weekend," he said.

Off track, the attractions include the Shannons Show 'n' Shine display, a vintage caravan show and a sold-out Legends Dinner.

"We're expecting more than 350 cars on and off-track, great racing from some truly top drivers and great weather. It's a weekend not to miss," Mr Collins said.

The community-run Historic Leyburn Sprints are supported through Southern Downs Regional Council and Tourism and Events Queensland's Regional Development Program as part of a growing calendar of events across the State.

Competition starts at 8am tomorrow and Sunday. Adult entry costs $20 per day or $30 for the weekend, children under 14 years admitted free.