Patrick said: “Something seemed to be on top of us. We looked around but it didn’t seem to be there. It seemed to kind of grab the car.

“I wound up the windows and the car began to smoke up inside. It smelt like dead bodies or something smelt really foul, like gas or something.’’

He said he felt as though his brains were being pulled from his head. When the car dropped to the ground it blew a tire.

The family hid in a bush and after about 30 minutes replaced the tire and drove to the Mundrabilla roadhouse, where truckie Graham Henley said he also had seen the bright light in the area in his rear-vision mirror.

It was hovering above The Basin on the sweeping stretch of road just flickering in and out between the trees,” he said. He said the family was in a state of shock and even their dogs were cowering in the car.

“The whole car smelt like bakelite or just like as if you’d blown a fuse,” he said.

“A soot was all over the car and there were four dents as though the car had been picked up by a magnet.

“I cannot explain it but all I know is that I saw four very terrified people at 4.45 on Wednesday morning.”

Police investigating the incident said the car had a dented roof and was covered with an ash-like material. Ceduna policeman Sergeant Fred Longley said Mrs Knowles and her sons were obviously distressed when they walked into the police station.

“They were in a terrible state — even though it was five hours after the incident. Something happened out there. Their car, even after being driven all that way, still had black ash — or dust — over it. Even on the inside. Where did that come from? There’s no soil like that out there, only sand.”

And Ceduna officer Sergeant Jim Furnell said the car had dents in the roof “as if something had landed on top”.

The investigation — and the theories

Two theories emerged. First, that it was debris from a meteorite, which would explain the ash and the smell. Second, light from a car beam refracted and distorted by warmer air lying over colder air.

A research physicist from the University of Wollongong, Glen Moore, told The Advertiser at the time it was probably a rare sighting of a falling, disintegrating meteorite.

The Knowles family’s description of a bright light, violent shaking, vehicle damage, smell and the deposit of powder-like material was consistent with the falling disintegration of a carbonaceous meteorite.

Bright lights spotted by tuna fishermen in the Great Australian Bight at the same time supported the theory. Nine months later a bus driver reported a similar light near Mundrabilla. Allan Brunt, former regional director of the Bureau of Meteorology, gave a much more banal — but still fascinating — reason: weather.

He said on both nights there was warmer air overlying colder air across a wide area of the Nullarbor Plain. Called a temperature inversion, it can refract and bends the light’s path, making it seem higher than it is. It also distorts its shape, colour, size and intensity.

Mr Brunt believes the Knowles family saw the refracted light of an approaching truck.

“It was the distorted image of its headlights which was so frightening and bizarre,” said Mr Brunt.

The rest was “their own imagination whilst in a state of fright”.

The tuna fishermen probably saw the refracted light of another ship and the bus driver, Mr Brunt believes, saw Jupiter. He said the flat desert conditions of the Nullarbor Plain make it an almost perfect place for UFO spotting.

What about the ash and damage?

Analysis of the ash found it wasn’t extraterrestrial. It was from the interior of a burnt-out brake lining. The blown tire was consistent with a high-speed tire blowout.

The dents on the roof were insignificant, and it couldn’t be established if they were there before the UFO report.

Sean said he was doing 200km/h to escape from under the UFO.

According to the manufacturer, the Telstar could never reach that speed on the ground. Tests in Adelaide — conducted with the car’s wheels off the ground on jacks — took the speed to 200km/h.

But — and here’s a big but — according to the 1990 UFO Report by Timothy Good, the “dust” was also analysed at the Philips Laboratory by Dr Richard Haines in July 1988.

He concluded the dust taken from the interior of the car was different to the dust sampled from the exterior.

And he found the interior dust was not from the brake system of the car. Unusually, it possibly contained sodium chloride — or salt — and the atomic element astatine, which is only produced synthetically. It would have decayed by the time the Knowles arrived at Ceduna, where the samples were taken, giving just a possible reading.

It did contain oxygen, carbon, calcium, silicon, potassium — and fibres of typical pipe insulation.

An officer later said just a few specks of dust had been recovered from the car, pointing out it had been driven 500km to Ceduna after the incident and townspeople had swarmed all over it, rendering it almost valueless for forensic evidence.

Investigation of the Knowles’ story was difficult for both sceptics and UFO researchers because they were reportedly paid by a TV station, which forced people to mediate with it to speak to the family.

What happened next?

Four months after the Knowles’ encounter, they had moved out of their Perth home, saying their former friends and acquaintances thought they were crazy.

They said the incident had cost them about $18,000, and they lost the car because they couldn’t meet the repayments. The six weeks away from home took the rest of their savings.

They claim a Wes Johnstone of Multi-Level Advertising took the car and promised to make them rich with promotional appearances.

“He told us it could be used in television commercials, a documentary and taken around shopping centres where people would pay to see it,” Faye Knowles said.

“But we didn’t get a cent; we don’t even know if the car was promoted at all, and now we have lost it.”

The 1984 blue Telstar was auctioned in June 1988 for $7050 to Gary Hancock, of Southside Motors. At the time, The Advertiser reported Mr Johnstone had stored the car for five months but hadn’t been heard of since February.

And Patrick said he was fed up with sceptics who disputed the UFO encounter.

“We are trying to forget the sharks who promised us money from our experience — they only wanted to use us,’’ he said. “We just want to get on with our lives, find jobs and settle down somewhere in Perth where people do not ridicule us in the street.”