Detroit — A favorite story making the rounds of Chrysler Corporation goes like this: An auto haul-away truck loaded with new Dodge Caravan minivans wends its way through the back-road hills in an Eastern state. For more than 30 miles it is tailed by a motorist. Suspicious, the truck driver makes a beeline to the Dodge dealership where he's to drop off his load.
The car, however, follows him right into the parking lot. Alarmed, the driver leaps from his cab and rushes toward the dealership, but he's caught short by his pursuer. ''I've been following you for miles,'' he says, ''to see where you were taking these vans. I'm going in and order one right now.''
The storytellers don't say whether he was successful, but chances are he failed in his mission. Dodge Caravans, along with companion Plymouth Voyagers, are the hottest new items on the market since perhaps Ford Motor Company's Mustang, which debuted 20 years ago this month.
If the Dodge dealer in question was typical of his colleagues around the country, all the arriving Caravans had already been sold and only served to chip away at his lengthening order list.
In fact, buyers are waiting two months and longer to get their hands on the new downsized vans.
Meantime, Chrysler is stepping up production at the only plant where they're made - Windsor, Ontario - and for the short term is planning to do something that has never been done in an auto-assembly plant before: three shifts.
Longer term, the company will convert a second plant to minivan production.
Introduced in January, the front-drive Caravan and Voyager right now enjoy a virtual monopoly in the new marketing niche. Volkswagen of America's Vanagon, a quite different vehicle whose engine is mounted at the rear, and a spate of substantially smaller minivans from Japan are its only competitors.
But starting in September, General Motors enters the minivan market with its Chevrolet Astro and GMC USV (utility sport van), to be built at a rate of about 200,000 a year in Baltimore; and Ford follows in January with its Aerostar ''compact'' van, also scheduled at about 200,000 a year in St. Louis.
Thus, by the 1985-86 period, US minivans will roll off assembly lines at a roaring rate of more than 600,000 a year, ensuring that they'll be far from passing fads. Chrysler could use more output now, but whether that will be needed when its larger competitors, General Motors and Ford, arrive on the scene is what perplexes its planners as they look ahead to the market a year or two down the road.
Based on early returns, however, it is evident that the small van is a vehicle whose time has come for a good many reasons:
* Compared with full-size vans, all of the new models are garageable. Moreover, depending on engine and transmission combinations, they offer fuel economy that often doubles that of their larger counterparts.
Caravan and Voyager, for example, are rated at 24 miles per gallon in city driving and 38 on the highway when equipped with Chrysler's 2.2-liter, 4 -cylinder gasoline engine and manual gearbox. With a larger, optional 2.6-liter, 4-cylinder engine, they still achieve a respectable 21 in the city and 30 on the road.
GM and Ford models will be slightly larger, and each will offer optional V-6 engines (also, Ford will have a diesel option). But with their base 4-cylinder gasoline engines, their mileage will be comparable to Caravan and Voyager.
* Despite their smaller overall dimensions, which enhance handling and maneuverability, the new breed of vans still sit high for good visibility and can carry more passengers, cargo, or both than mid-size or full-size standard passenger-car station wagons.
The Ford and Chrysler vans can be optionally equipped to carry seven passengers, while GM boasts that its Chevrolet-GMC duo can carry eight.
* Unlike larger vans, the newcomers are far less ''trucky'' and drive more like passenger cars. That is not by accident. A Chevrolet executive confides that large station wagons will probably be swept under by the rising tide of minivans.
Still, the GM and Ford minivans, both featuring traditional rear-drive layouts, should appeal to commercial customers as well, in that they can carry heavier cargoes and haul heavier loads than can the front-drive Chrysler models.
Front drive, however, provides several advantages in its station-wagon, as opposed to commercial-van, garb. Because both transmission and engine are up front, there is no need to raise the floor to make room for a drive line to the rear, as is necessary in the GM and Ford configurations. Thus, entering and exiting Caravan/Voyager is almost like stepping into an ordinary car, while an extra step up is required in the rear-drive models.
* Accouterments and options are designed to appeal to personal-use buyers. Each of the Big Three's minivans has its own list of niceties. Among them are electronic dashboards, automatic side-view mirror switches, plush seats and interiors, and even, in Ford's Aerostar, separate radio jacks and earphones for rear-seat passengers.
Although dimensionally quite similar, each of the three lines stands out from a styling standpoint. Aerostar is the most rakishly aerodynamic, with its ''anteater'' front end, while GM's entries are aerodynamically rounded up front but severely chopped off in back.
Among the three, only Chrysler's minivans feature stacked front quad headlamps.
Early reports indicate that Chrysler is achieving exceptionally high-quality levels at its totally revamped, highly automated Windsor plant.
Because GM and Ford are also gutting existing plants and inserting advanced equipment and systems, their quality levels should also be high.
New paint lines at all new United States minivan facilities sharply upgrade exterior finish treatment.
The new minivans also overcome a longtime problem van owners have faced: premature rusting in vital areas. Ford plans to use plastics for Aerostar's hoods and tailgates, for example, and Chrysler boasts that its entries contain more two-sided galvanized steel in major body panels than any other vehicle ever built.
The final vote in the minivan's favor may well turn out to be price. Base stickers on the Chrysler models start at around $9,000, and a fairly well-equipped model can be bought for less than $12,000. That's not cheap, of course, but in today's market it buys much more vehicle for less than many a smaller car having far less passenger capacity to carry people in comfort.
That's why the budding minivan craze is not likely to end soon.