Beginning in late May, Warner Bros. will unleash upon 800 neighborhood theaters an unknown movie from Down Under called "The Road Warrior." "The Road Warrior" is the sequel to "Mad Max," an automotive mayhem movie set in a horrific future and directed by George Miller. It was made in 1979 for $358,000 and has grossed $20 million worldwide.

Despite a run on Home Box Office and bookings in scattered theaters, "Mad Max" was hardly noticed here. No Australian film, in fact, has ever had what is known as a "wide break" in the United States. Warner's intends to change all that.

"We're handling 'The Road Warrior' like a big picture," says Joseph Hyams, Warner's vice president. "We're going out with 800 prints and saturation booking, starting in the Southeast and moving west and then north. There'll be a big television ad campaign. This is a picture that doesn't have to be nursed the way the more serious Australian films had to be."

No indeed. "Warrior," a high-octane car opera, stars Mel Gibson, the dark-haired soldier of "Gallipoli," as a socially benumbed but invincible hero of a wasteland of rape, chains and villainy. In this paean to the individualistic spirit, gas-crazed human vermin are armed with crossbows, the prettiest girls die first and hope is strictly for sissies. The baleful Gibson--wife and child previously murdered in "Mad Max" and current pet mongrel not long for this world--looks in his tattered motorcycle leathers like a tougher version of Harrison Ford in "Raiders of the Lost Ark." In fact, he looks like he could eat Harrison Ford for breakfast.

Warner's is betting that the marvelous characters and nonstop action of "The Road Warrior" will bemuse the critics and pack the theaters.

If so, there are plenty more where it came from. American movie costs are up, and production is at best stable. But Australia--buoyed by tax incentives set in place by the government last year--will triple its film production this year.

"There's no doubt that Australian films remain the flavor of the month in Hollywood," says Francis O'Brien, a former congressional staffer who was the executive producer of Peter Weir's "Gallipoli." "There's a lot of talent there, and films can be made cheaply. As for 'Road Warrior,' it's definitely going to be the biggest movie ever to come out of Australia."

A year ago, that was being said about "Gallipoli," and indeed the industry Down Under sets new records at nearly every turn. Weir's tale of Australian innocence lost in the trenches of World War I was the most expensive Australian film in history at $3 million. It was also the first to have a major studio--Paramount--provide distribution and advertising backup. It has already returned $6 million in the United States and $7 million abroad.

The record had been $1.6 million only two years before, with Fred Schepisi's "The Chant of Jimmie Blacksmith," a brutal tale of an ab-origine driven on a murder spree. "Breaker Morant," Bruce Beresford's ironic story of three Australians accused of war crimes by the British Empire they served, was made for only $800,000 in 1980. It has returned $6 million in the States alone, with another $1 million expected from cable TV.

Such budgets continue to astonish Hollywood, where the average cost of a motion picture last year was $12 million, and the mean cost--excluding very expensive projects such as "Reds" or "Ragtime"--was still $8.5 million.

Equally astonishing is that, between 1950 and 1970, fewer than a half-dozen features were shot in Australia--notably Stanley Kramer's "On the Beach" (1959) and Fred Zinnemann's "The Sundowners" of 1960. Since 1971, however, there have been more than 100 movies made there--the direct result of the establishment that year of what is now the Australian Film Commission. The government simply decided to start funding its own film industry, and the outpouring has surprised even the Australians.

Most of those 100 movies remain unseen in America, however. Audiences in large cities may have been offered a half-dozen, and cable TV carried "My Brilliant Career" and others, but Australian films have otherwise been ignored here, in contrast to their successes in Japan and Europe. "Breaker Morant," now regarded as a classic, opened in New York quite by accident. It was a last-minute, low-budget replacement for an American film that had turned out to be a disappointment. The disappointment was "Heaven's Gate," which had cost $40 million.

There is now a movie house in New York--the D. W. Griffith Cinema--that for the past year has been showing Australian movies exclusively. They have also been the subject of many film festivals, like "New Australian Cinema," playing through April 14 at the American Film Institute.

"What the Australians are giving us are good stories, good acting and strong production values. They're not being sold on gimmicks," says Ernest G. Sauer, president of Satori Productions. "The whole country is like a very large repertory company."

Sauer has just returned from the Manila film festival, where he obtained distribution rights for five Australian films. "They're good, all right," said Sauer. "The question is, does any one have the potential to make it big all across the country. That's why were opening ours in the top 10 markets."

Australian movies are more than cheap and plentiful and strongly plotted: They are, as Hyams puts it, "foreign films that don't need subtitles," and they carry the fascination of a robust, faraway culture with a slightly different point of view.

It was point of view, more than technique or actors, that brought the Italian cinema to recognition after World War II, got Godard and Truffaut and French movies noticed in the 1950s and drew audiences to Forman and Polanski and the Eastern Europeans in the '60s. Now it seems to be Australia's turn.

"Robust" is a word often applied to Australian life, and it seems equally descriptive of its movies. In the spirit of Judy Davis in "My Brilliant Career," and the poetry-writing sergeant of "Breaker Morant," or the open-faced lads of "Gallipoli," the island continent is exporting a raw muscularity often associated with an earlier America. Australian actors are rugged-looking, Australian backgrounds vast and unfamiliar and the stories told reflect the rough and tumble of a nation of adolescent virility.

Bruce Beresford has a simpler analysis: "I am not aware of any particular robustness that our films have in common. What has happened, what we have in common, is that our budgets have been very low. We haven't been able to indulge ourselves. We've had to come up with plots and characters and strong situations."

Beresford's first film, in fact, went beyond robustness into what is widely adjudged to be vulgarity. "The Adventures of Barry MacKenzie" is about a crass Melbournian who journeys to England, whereupon he disgraces himself comedically in a number of incidents, including dropping his trousers on English TV. "Barry MacKenzie" appalled critics in Australia, but made a great deal of money. (When Mike Clark of the American Film Institute asked to view the movie in Canberra last year, the librarian said: "Are you sure you want to see that?")

"That movie totally wrecked me for a while," Beresford says now. "It was really a dreadful film, and I could hardly get any work after that. They had me typed as a bucolic rustic. The worst thing that can happen to you in Australia is that your movie makes a lot of money, and gets bad reviews. Then the government won't give you any more money. I had to go off and make TV films until I was able to redeem myself with 'Don's Party' in 1976.

"But for all that, 'Barry MacKenzie' was the movie that established that Australians would go to see a movie about Australians," Beresford adds. "Before that they figured Australians would always rather see Cary Grant. It was quite a joke, the idea of showing Australians a movie with Australians in it. Our accents, and all of that."

"I think what happens in Australian movies is quite unconscious," says George Miller. "I am quite taken aback by that word 'robust.' In fact, our film culture draws equally from Europe and Hollywood. We're a hybrid culture. I have been asked a number of times why our movies have a different look. Frankly, I just think the light there affects the Kodak stock differently." Is he serious? "Well, that's a short answer, anyhow."

It was not the quality of Australian light, however, that led Miller to create the character of Mad Max, who if he is not the Australian Everyman must at least be some version of the Australian Superman.

"Well, in Australia we have a violent car culture, whereas maybe in the States the violence is in the gun culture. Max comes out of that. We have these big, wide roads, and there is a high percentage of death on the highways. Yes, there is some form of socially accepted violence on our roads.

"This time, though, Max is much more mythological, and we were very conscious about that. He's like a samurai, or a knight, or an American gunslinger. We're only now getting into contemporary topics, you know," Miller said. "Before, there were a large number of Australian period films. It was because our industry was new, and there was a rush to retell our own past, to capture it and define it for Australians. Now we're moving ahead."

One concern is that the new crop of Australian directors--now regarded as a national resource--will move not only ahead, but away.

Beresford has been living in New York for a year, and has just completed shooting a film with Robert Duvall in Texas titled "Tender Mercies." His next project is a biblical story called "King David," under contract to Paramount.

Fred Schepisi has just completed a $10 million project called "Barbarosa," with Willie Nelson and Gary Busey. Gillian Armstrong, who directed "My Brilliant Career," has agreed to make two films in the United States. And Peter Weir, the hottest of the Australians, is being courted aggressively. One idea brought to him: the story of the American Revolution.

"I think they'll move around, they'll take the work, but they won't leave Australia for good," says Francis O'Brien. "They really love their freedom, and you can't get that in Hollywood."

"My daughter was with me in New York last year," Beresford said. "One day she went out and bought herself a plane ticket home. She said to me, 'Dad, I just can't stand living in a city without beaches.' You know, in Sydney we've got surfing, sailing--all of that."

Part of the charm of Australian films is a barely concealed combativeness, a wise-guy streak, a disinclination to accept any form of social class system. This extends beyond their movies.

"Australians can be very tough, even on each other," said one American who spent time there. "They have sort of an 'us-and-them' attitude. This extends to their own people. Suddenly, if you're a success, you become 'one of them.' David Williamson is their best known playwright. Beresford has filmed several of his plays, and he wrote 'Gallipoli.' So David goes home to a cocktail party in Sydney, and somebody started saying, 'So you think you're a big deal, now?' or something. A fistfight actually resulted. David is about 6-7, but he's a gentle guy. He was pretty upset."

The Australians are trying to be smart about their initial success. They would like to keep control of their industry, keep making movies about Australia and let the world pay to see them.

The government, meanwhile, is tightening its purse strings, and seeking increased control of scripts and of outside investors in an effort to avoid what is being called "Canadazation." The Canadian government also offers tax assistance to filmmakers, but the result there has been a number of movie projects designed more for investor shelter or profit than anything else.

"Our industry has to attract more private money, but we don't want to end up making 'deal pictures,' " says Miller. "You can't have accountants and lawyers as producers. The common denominator of all successful films is that somebody was enthusiastic about the subject."

Francis O'Brien expects to return soon to Australia on another film project, and he expects things to be different there. "We'll be paying more, although still not anything like Hollywood. An outsider can expect to pay triple fare to the unions. Of course, we paid 40 percent loading to Actors Equity for 'Gallipoli,' and that only amounted to an extra $20,000.

"There are really only a few top film crews, and they're booked. Some of the tax laws are quite unreasonable, such as a provision that you have to make the movie and release it in the same year. And there will be more competition now. You'll have to be faster, more like in Hollywood. When I was there in 1979, every script in the country came to me to read. Now I won't be the only game in town."

It seems likely that Americans will be seeing more movies from Australia than ever before. At the very least, 30 new features this year will not be lost on broadcast television, or the competing pay-cable channels, who need productions in English and are already running short. The Australians, for their part, have also bent a little: Both "Mad Max" and an early Peter Weir movie called "Cars"--about an Australian town that wrecks the automobiles of tourists passing through--had to be dubbed for American audiences, their accents were so thick.

The English of "The Road Warrior," however, is perfectly understandable.

Whether Miller's bizarre vision of the future can be as widely understood remains to be seen. It may also be the future of mass-market Australian movies in the United States, and Warner Bros. will have their answer by June.