Deco derby thrills crowds + VIDEO

With a hiss and a roar the race was on, as carts whizzed through Napier CBD for the annual Soap Box Derby.

Children, and parents with their home-made carts converged on Tennyson St this morning for the popular Tremains Art Deco Festival event.

Thousands lined the street as drivers were asked to start their "engines", signalling chaperones to begin pushing competitors in their carts.

When they let go, gravity took over.

The race was nothing new for the Parsons siblings - eight-year-old Leo has been racing since he was three, while Maggie, 13, has been competing since 2008.

She won a number of heats today in a spaceship inspired cart built by her father Stu, which required her to lie down face first in the cart's enclosed shell as it hurtled down Tennyson St.

There were no nerves, instead the Napier Girls High School student said the key was to "really focus on getting across the finish line."

As each heat finished, the carts were wheeled back to the top of the race where spectators could gush over the home-made masterpieces, from small three-wheelers, replicas of famous cars like Brum or the World's Fastest Indian, and even a scaled down Bugatti.

First-timer Christchurch resident Eliza Dixon, 14, had raced the blue two-thirds scale replica of a Bugatti Type 35, cheered on by her extended family.

The cart had been a family effort, which took her cousins three years to build after their work was interrupted by the Christchurch earthquake.

Although he had been too old to race the cart after it was built, Binney Matthews, 19, said it had been a lot of fun to be involved as a cart pusher for his cousin.

While other carts had more humble origins their drivers were just as proud, like 10-year-old Bailey Greeks.

Destined for the dump, his small black cart had been saved and given a new lease of life by Bailey's father - giving Bailey three years of enjoyment competing in the event.