When Mary Lou Branch got rid of her Audi last fall, she says she went in for something "much more exciting" than the luxury import. Something equally as comfortable, she said, something with easier handling and "a better-looking interior" to boot.

She bought a truck."It's a 1988 Jeep Cherokee," said Branch, an Irvine, Calif., secretary who traded in her car in October. "I had checked into a station wagon, but the old family vehicles seem to be getting replaced. The Jeep seemed to be nice, so - I don't know - I guess I just decided on a change."

And in the process, she also became one of an increasing number of women who are eschewing expensive cars in favor of sleek, new light trucks - pickups, vans and sport utility vehicles - that have overwhelmed the U.S. automobile market.

Young and old, married and single, women across the United States have been purchasing light trucks in record numbers over the past few years, drawn primarily to a look they say is as appealing as the best of luxury cars without diminishing traditional truck qualities.

"A man that buys a B-350 full-size pickup buys it to haul," said Elaine Pearson, a senior truck planner at Chrysler. "A woman would buy it for the same reason, but women also like the image. Trucks are becoming sportier and better equipped: They have power locks, power windows, rear defrosters. A few years ago, trucks were pretty Spartan . . . They're more user-friendly now."

Consequently, about 936,000 light trucks were sold to women in 1988, representing 19 percent of total light truck sales, according to industry estimates. That includes 327,000 compact vans and 214,000 compact sports utility vehicles.

Such presence in the light truck market is a far cry from what it was during the 1970s, when studies indicated that women accounted for only about 2 percent of light truck buyers.

Moreover, this boost in women purchasers accompanies an overall boom in the light truck industry. Light truck sales set their fourth-straight record during the 1988 model year, rising 4.51 percent to 4,838,538. Sales for the 1987 calendar year also rose, to 4,962,938 units, up from 4,875,708 in 1986.

Yet, as dramatic as the rise in women light truck buyers appears, it is a leap that industry analysts predict will be dwarfed by figures 10 years from now. "Our projection for female truck ownership for the year 2000 is somewhere over 30 percent," said Richard Anderson, the market planning manager for Ford's light truck division. "They are a very important part of the market."

Women are having their greatest impact in the compact sport utility market, where they already account for 30 percent of total sales.

Indeed, of the 81,349 Suzuki Samurai utility vehicles purchased last year, nearly 40 percent of them were bought by women, prompting Jean Pellegrino, an analyst at J. D. Power & Associates, to declare the trendy vehicle "the outstanding leader among sales to women."

Women also buy about 20 percent of the pricier Dodge Raider, Chevy Blazer and Jeep Wagoneer models sold each year, according to Pellegrino.

Analysts are quick to note that these expensive specialty trucks are being bought by professional women who can easily afford high-priced automobiles. "It's that whole yuppie thing that has driven the light truck market upscale," remarked Pearson. "That's why the sport utilities sell well."

Yet, in spite of the hefty sums now going toward the sleek sport utility vehicles - the Jeep Cherokee, the Bronco II, Nissan's Pathfinder and the like - industry observers credit the relatively cheaper compact vans and mini-vans for spurring the light truck craze among women.