That's why a team of Parramatta High students, who stormed their way to victory in the annual national high school race for model vehicles powered only by sunbeams, have already started designing an even faster vehicle to defend their crown next year.

Weighing just 1.8 kilograms, Parramatta High's car, dubbed Solar Dog, left 31 competitors from across the country in the shade last month by completing a 100-metre Adelaide course in 19.58 seconds, half a second ahead of a machine built by Queensland's Shalom College.

''It was overwhelming,'' said Parramatta's 14-year-old Shannon Flexman.

''It was the first time since the competition started in 1990 the race was won by a NSW school, and the first time in years it was won by a Government school.''

Building a solar car for the race had been the class project of 16 Parramatta High Year 9 design and technology students.

After rugged testing involving weekend and after-school work, Solar Dog, built by Shannon and classmates Harshul Dalal, Mirza Juddani and Edward Yoo, was selected to go to Adelaide.

But on arriving, the students were horrified to discover many private schools had employed advanced but expensive carbon fibre materials to shave weight from highly aerodynamic designs, allowing them to build car bodies weighing as little as 150 grams. ''We just used aluminium and plastic,'' said Shannon. ''A lot of the other schools had some good ideas ... but they just didn't go.''

Their teacher, Mr Mark Dabbs, attributed Parramatta's victory to ''a lot of practice and a lot of experimenting''.

While he estimated some competitors spent ''thousands'' on high technology, his students had to work with parts found in the storeroom and a $500 Shell sponsorship.

He is now hunting for more sponsors to help his students develop an even faster solar car for next year's race, to be staged in Sydney.

''The opposition has seen our car now and they will copy it, so we will have to come up with new ideas,'' said Mr Dabbs, noting that even in the world of model solar car technology, industrial espionage is a worry.