Fans of the battery-powered car which made Merthyr Tydfil famous have been meeting in the town with their machines.
The C5s have generated considerable interest
Lovers of the historic Sinclair C5, which was made in the Hoover factory, converged on the town for a rally with a difference.
A two-day event is being held at the Trevithick Visitor Centre, and owners from across the UK are expected to attend on Saturday and Sunday.
The one-seater C5 was launched in 1984, with the hope that it would revolutionise travel, but it failed to entice buyers.
Event organiser Glyn Bowen said many of the drivers had been delayed on Saturday because of a major accident on the M4, but he hoped there would be a good turn-out.
"Some of the Hoover staff who were involved in assembling the C5s are also coming along," he said.
"Anyone who has a C5 is welcome to attend."
The Trevithick centre is an appropriate place to hold the event, as the Hoover factory at Pentrebach can be seen from Merthyr Tram road, where Richard Trevithick's pioneering Penydarren locomotive became the first steam locomotive in the world to haul a load on rails in 1804.
Andy Harper, the world's only remaining authorised C5 parts dealer and engineer, will be travelling from his home in Kent for the convention.
He worked on the production of the C5s and will be making his first trip back to Merthyr since the vehicles started coming off the production line in late 1984.
"I think the C5 has always been pretty cool, but the press made it uncool," he said.
The C5 was a commercial disaster
"They said that it was a dangerous invention when in fact, in 20 years, nobody has ever been seriously injured while driving one."
For all its novelty value, the £200 Sinclair C5 failed to make a fortune for inventor Sir Clive Sinclair.
Only about 12,000 were ever produced, but now collectors are snapping them up as investment items.
Princes William and Harry were lucky enough to have one at Kensington Palace as children, and Mr Harper travelled up to service it several times.
Sir Clive Sinclair - who created the one of world's smallest calculators in 1972 and the pocket television in 1984 - is still inventing.
Only a few weeks ago, he unveiled the world's smallest and lightest foldable bike - weighing just12lbs built to support riders weighing up to 17 stone.