Boston — America finally may be on the road to easing, if not ending, its $3.2 billion-a-year stolen-car traffic jam.
And in the process Massachusetts could lose one of its least cherished labels -- that of the nation's auto theft capital.
While the bottom has not fallen out of the vehicle larceny market, the Federal Bureau of Investigation's (FBI) preliminary figures for 1981 indicate a modest 4 percent drop in car and truck thefts across the United States. This is the first such decline in six years.
But despite the reduction, more than 1 million vehicle thefts -- one every 29 seconds -- took place last year. In New York City, for example, a car was stolen about every five minutes and in Boston, which has less than one-twelfth the population, there was an auto larceny every 24 minutes. In Boston, New York, and many US cities with populations greater than 500,000, more autos were stolen in 1981 than in the previous year.
But in medium-size and smaller cities, the FBI preliminary figures released this spring indicate an overall decline of 5 percent to 9 percent in car thefts.
Although obviously encouraged by these figures, law enforcement officials and others concerned with car-theft prevention are generally cautious.
Many, like Paul W. Gilliland, president of the Illinois-based National Auto Theft Bureau (NATB), note that ''even with this perhaps temporary improvement, more than 1.1 billion vehicles were stolen, 1.2 million had parts taken from them, and 1.3 million others were broken into.''
''We must not reduce our aggressiveness to control vehicle crime,'' Mr. Gilliland says. He urges a ''closer working together of law enforcement agencies , the NATB, and private industry.''
The 4 percent decline in vehicle larcenies last year contrasts with a 1.6 percent drop in 1980. So far it is uncertain whether car-related larcenies, including thefts of items or accessories from vehicles, also decreased in '81. Such thefts added to those of whole vehicles, accounted for 45 percent of all larcenies in the nation in 1980, according to the FBI.
One in every 143 motor vehicles registered in the US was stolen in 1980 and one in every 43 was either taken, broken into, or had one or more parts stolen.
While the number of vehicle larcenies may be leveling off, the proportion recovered continues to drop, as it has for the past quarter-century. In 1957, for example, 92 percent of the 282,800 cars and trucks stolen were found and returned to their owners. Last year just 55 percent of the 1.1 million were recovered.
This change is generally attributed to what police officials view as ''increased professionalism'' among car thieves. They point out that in many instances a vehicle is worth more as parts than it is whole. As a result, so-called ''chop shops'' have sprung up which in hours, if not minutes, can reduce a stolen auto to its salvageable components including scrap metal.
Such operations are usually well hidden, but state and local police crackdowns are progressing. Within the past six months Boston police have shut down at least nine chop shops, explains Robert O'Toole, the department's informational services officer.
Despite this effort, the number of vehicles stolen in Boston in the first quarter of 1982 (January through March) totaled 5,208, over 100 more than in the corresponding period in 1981. FBI figures for 1980 rank Boston eighth among US cities in vehicle thefts and first in such larcenies per 100,000 population.
Yet Massachusetts as a whole has shown a modest decline in vehicle thefts over the past three years, from 62,500 in '79, to 57,500 in '80, to 52,538 in ' 81, according to the state police.
Trailing the Bay State on the stolen-vehicles-per-100,000-population chart are Rhode Island, New York, California, New Jersey, Nevada, Alaska, Connecticut, Hawaii, Michigan, the District of Columbia, and Texas, in that order. All 12, including Massachusetts, exceed the national average of 494.6 vehicle thefts per 100,000.
The safest state in terms of car larcenies, in 1980, was South Dakota, with a 168.6 ratio, followed by Mississippi, North Dakota, Arkansas, and West Virginia.
Contributing, perhaps substantially, to the declining recovery rate for stolen vehicles is a heavy traffic in export of late-model stolen cars. NATB officials estimate that 20,000 cars a year are slipped into Mexico.
They and some law-enforcement officials are critical of current US Customs regulations that do not require advance listing of vehicles being shipped. Such reports need not be filed until 72 hours later and information filed is sketchy.
Critics suggest that those wishing to export a vehicle be required to file detailed data, including the vehicle identification number (VIN) at least 48 hours before departure. This would could shrink the stolen car market considerably, maintains Thomas J. Carr, manager of safety for the Motor Vehicle Manufacturers Association of America.
''Not all cars reported as stolen are actually stolen,'' he explains, adding that fraud, under which owners behind in their payments sometimes arrange to have (their cars) disappear,'' is a contributing factor to the high vehicle theft statistics.
Police and insurance industry officials blame much of the high incidence of car, truck, and motorcycle larcenies on what they view as ''lax sentencing.'' Stiffer penalties, they contend, are needed.
Efforts to push through statutes requiring the licensing and periodic inspection of vehicle salvage businesses have generally failed due to stiff opposition from scrap metal and salvage parts industries. Laws requiring vehicle motors to contain the VIN are widespread but in no state is the indelible stamping of this numerical label on the body of cars and trucks mandatory.
Legislation now pending in Congress, and supported by the auto insurance industry and others concerned over the increasing trafficking in stolen vehicle accessories, would compel manufacturers to put the VIN on every major vehicle component, such as fenders, trunk floor, doors, radiator, and chasis.
Prospects for passage of the measure, however, are slim since the Reagan administration appears cool to the idea that earlier it had supported, outwardly at least.
The 1981 overall dip in car thefts across the US resulted in large part from ''the great deal of attention given to the subject,'' says Robert L. Barber, an assistant vice-president of Liberty Mutual Insurance Company. ''Car owners are more alert, judges are more aware of the problem, and police are more active,'' he elaborates.
FBI vehicle-theft statistics show that 65 percent of those arrested were under 21 and 45 percent of the youthful offenders were under 18. But the number of young vehicle stealers continued to drop as it has in recent years. Mr. Barber and others in his industry and throughout law enforcement interpret this as meaning ''fewer vehicles are being taken for joy rides, and more taken for sale in the black market or cut up for parts.''