Mr Denne said he had dodged apples at least twice in a 100km/h zone on Illawarra Road, between Perth and Longford, during the past 18 months.

The motorcyclist, who has almost 50 years' experience, said he was unaware if the people inside cars had deliberately targeted him.

However, the incidents have occurred during the day, on a straight stretch of road and the apples were uneaten.

The first time involved one apple, and the second time it was two apples at once.

The fruit hit the road as Mr Denne was passing the cars, riding in the opposite direction.

"You just see the car coming and stuff coming out of the rear window," Mr Denne said.

"It was really lucky for me, because it's a four-lane stretch of road.

"If it had been only a two-lane road and they had thrown stuff out at me, it might have been a totally different outcome.

"By the time it happened, the cars were gone and it was too late to go around and do anything about it.

"But if you get hit, there's not much you can do either.

"You're probably lying on the ground by then. A softball thrown out of a car would have the same effect if it hit a person on a motorcycle in the right spot in the chest - that would kill them."

He said an intersection at Perth was also dangerous, with vehicles often ignoring the give-way sign at Youl Road and Drummond Street.

Mr Denne suggested that authorities make people take a motorcycle course before attaining a car licence, to enable them to understand how motorcyclists had to be extra aware about everything around them. "There are that many things they have in modern cars for people to do while driving, that it takes their attention away," Mr Denne said.