Minivans tend to be as safe as large cars in vehicle crashes, according to a new report on vehicle safety, soon to be published by the National Highway Traffic Safety Administration (NHTSA).

The report, "Safety Programs for Light Trucks and Sport Utility Vehicles," comes in the wake of criticism that the government is moving too slowly to strengthen crash-protection standards for vans and other vehicles classified as "light trucks."

The report's conclusion is being knocked by auto safety advocates, who contend that minivans and other light trucks are more dangerous than cars because the government has lower standards for light-truck safety. But NHTSA argues that its survey of fatal U.S. traffic accidents from 1985 through 1988 upholds its findings.

At issue are products such as the Dodge Caravan minivan, Ford and Toyota pickup trucks, and four-wheel-drive sport-utility vehicles, such as Chrysler Corp.'s Jeeps. The government calls those vehicles "LTVs" -- Light Trucks/Vans.

Small vans accounted for 120 deaths per 1 million registered vehicles over the three-year survey period, compared with 123 deaths per 1 million registered vehicles in the "large-car" category, according to NHTSA. All vans, including large models, accounted for 133 fatalities per 1 million registered vehicles, compared with 209 deaths per 1 million for all cars.

However, NHTSA says that the death toll for LTVs as a group was 210 people per 1 million registered vehicles. Boosting the LTV deaths were fatalities in small pickup trucks and sport-utility vehicles.

Says NHTSA: "The fatality rate for all light trucks is not appreciably different than it is for passenger cars, and the rates for four out of five types of LTVs are lower than for either small- or medium-sized passenger cars."

But in several major categories, NHTSA concedes that minivans and other LTVs are not subject to the same safety standards applied to cars.

Those standards include side-impact barrier protection, requiring the installation of steel beams or other crash-protection devices in side doors; passive-restraints, requiring the installation of air bags or automatic seat belts, and tougher roof-crush resistance construction, to help protect vehicle occupants in roll-over accidents.

The difference in standards occurred because, "In NHTSA's early years, the agency's regulatory and research approach was based on a clear distinction between the design and intended purpose of passenger cars and light trucks," the report says.

It continues: "Unlike passenger cars, light trucks were viewed as being designed and used primarily as cargo-carrying vehicles rather than as people-carrying vehicles."

But today, according to the report, minivans and light trucks basically are used as people haulers. As a result, NHTSA has proposed stronger LTV standards and expects to implement side-barrier protection and roof-crush resistance rules in September 1991.

The agency expects the standard installation of air bags or other passive-restraint devices in LTVs, beginning in September 1993.

That timetable is too slow, says Michael Johnson, a member of the vehicle safety staff at the Center for Auto Safety (CFAS), a Washington-based auto-safety advocacy group.

Johnson says that haste is needed in the rule-making because LTV sales are increasing every year. Sales statistics tend to support his argument.

A decade ago, LTVs accounted for less than 10 percent of all new vehicles sold in the United States, according to figures compiled by the Motor Vehicle Manufacturers Association (MVMA) in Detroit. But in 1989, LTVs constituted 33 percent of the 14.8-million passenger vehicles sold in this country, MVMA numbers show.

"It's irresponsible. For a long time now, consumers have been using these light trucks as passenger vehicles; but the government has chosen to ignore how these vehicles are being used," Johnson says. NHTSA's finding that minivans are as safe as large cars, he says, is misleading.

"As a group, minivans and vans are larger than cars, which means that they might fare better in accidents. But I suspect that the real reason for NHTSA's finding is that the people who buy minivans are safer drivers," says Johnson.

"A person with seven children in a minivan is not likely to go speeding around like a person in a Mazda Miata, who is trying to test the performance of the car," he says.

The existence of dual safety standards undermines LTV safety even in instances where those vehicles share the same standards with cars, some consumer advocates say. Take the matter of seats. Both minivans and cars are covered by Federal Motor Vehicle Safety Standard 207, which requires that vehicle seats meet certain standards to resist breakage in accidents.

But there is some reason to believe that the standard may not be evenly applied, or might be inadequate to ensure seat safety in minivans, CFAS officials say.

The center, for example, is asking that the government recall 1 million 1986-1989 Chrysler minivans to check rear seats that the center says can collapse in vehicle crashes. In one such Pennsylvania accident last February, a 2-year-old child was thrown from a 1987 Plymouth Voyager SE minivan when his seat collapsed.

Washington (Pa.) County Coroner Farrell Jackson, in a letter to consumer advocate Ralph Nader, said that the child was properly belted, but that the child-protection devices proved useless "because the rear part of the seat collapsed, letting the child loose from the seat, propelling him out of the vehicle into a creek 35 feet away."

The child died from hypothermia, stemming from his time in the cold creek. There were no lacerations or other injuries that contributed to his death, Jackson wrote.

Had the seat held, the child probably would have survived the accident, says Jackson, who called the seat "flimsy and poorly constructed and ... unsafe for public use."

NHTSA has begun a preliminary investigation of the Chrysler minivan seats. The company says it is cooperating with the investigation. Chrysler officials maintain, however, that their minivan seats and their minivans in general are safe.

Chrysler minivans "already meet" car standards for roof-crush resistance, which require that a vehicle's roof be able to withstand 1.5 times the vehicle's weight, says Albert J. Slechter, Chrysler's technical affairs director in Washington. Chrysler's minivans also meet car standards for head restraints, which have been finalized, but won't take effect until September 1991, Slechter says.

"We don't have the door beams for side-impact barrier protection. We question whether or not they are needed," because minivans and other LTVs ride higher than cars, says Slechter. However, Slechter says Chrysler will not oppose the proposed implementation of LTV side-impact barrier standards in September 1991.

"We're going to do it and then wonder why we did it, because we think it has marginal value," Slechter says. "Just because a vehicle does not meet a certain standard does not mean the vehicle is inherently unsafe." However, he says Chrysler will go along with all of NHTSA's proposals to upgrade minivan and light-truck standards.

"It's not going to be the same contentious battle this time around as it was for cars," says NHTSA deputy administrator Jeffrey R. Miller, commenting on the last two decades of efforts to improve car safety. "The debate {on the question of improving LTV safety standards} this time around seems to be on 'when' we will do it, not 'if' we will do it."