After two decades of focusing their technological efforts on pollution control and fuel economy, auto manufacturers are poised to create a generation of radically different cars that promise dramatic improvements in braking, handling and acceleration.

Some of the components of these new cars, such as computerized antiskid brakes and full-time four-wheel drive, are already on the market. Other, more exotic, innovations are on their way to the showroom.

For instance, the three leading Japanese car companies -- Honda Motor Co. Ltd., Mazda Motor Corp. and Nissan Motor Co. Ltd. -- are planning to introduce four-wheel steering in the American market in the 1988-model year.

Just behind, being designed or tested in prototypes, are such devices as "active suspensions" that automatically adjust the car's ride and handling to speed and road conditions; supermagnets that reduce the size and weight of electrical motors while increasing their power and reliability, and multiplex electrical systems designed to eliminate myriad wires found in cars and trucks.

"Some people say: 'They don't make cars like they used to,' and they're right," said Gary W. Dickinson, director of engineering for General Motors Corp.'s Chevrolet-Pontiac-Canada Group.

Auto technology has been making dramatic advances since the early 1970s, Dickinson said. But the drama often went unnoticed, because most of the changes were made to reduce exhaust emissions, improve fuel efficiency and meet new federal car safety standards, he said.

"We've converted virtually the entire lineup of GM cars from rear-wheel drive to front-wheel drive" to reduce overall car size without significantly reducing cabin space. "We've improved safety and fuel economy. But the things we've been working on have been more related to societal needs, and those things don't get much notice," Dickinson said.

With the mileage and emissions-control battles seemingly won, and with the apparent conclusion this year of the air bag war that raged for nearly two decades, auto makers are turning their attention to technologies that enhance vehicle performance, value and ease of operation.

The key to many of these advances is the microchip -- the tiny electronic device that is the heart of today's computer industry and is increasingly becoming the heart of many cars.

Connected to sophisticated sensors, the chips can register changes in such things as engine performance or steering angle and make adjustments at lightning speed.

"The auto makers first used electronics to control the ignition system, and then they went to electronics to control carburetion and fuel-injection systems," said Bill Kersten, vice president for technical services at the Reston-based National Institute for Automotive Service Excellence.

Fuel injectors, for example, precisely meter the amount of fuel going to engine combustion chambers, where the fuel is mixed with air and burned. Precision metering means a better air/fuel mixture, which means a better burn, which means a more efficient production of power.

Auto makers also used computers to control auto emissions systems, Kersten said. "For a while, many of these systems operated independently of one another." But now, all of these systems -- ignition, fuel-injection and emissions -- are controlled by one computer, "a kind of Big Brother" that watches over most of the car's engine functions, Kersten said.

"Everything is becoming more and more electronic. I stand back and look with wonder at what computers do in a car," Kersten said.

If the auto makers have their way, computers will be doing more. Most of the major players in the U.S. car market have so-called concept vehicles loaded with electronic devices. The purpose is to test the efficacy of the devices and their acceptability to the marketplace.

GM's experimental Pontiac Pursuit, for example, is a 200-horsepower car equipped with electronic four-wheel-drive and "steer-by-wire" systems, among other microchip-laden goodies.

The Pursuit's "steer-by-wire" eliminates the shaft that connects the steering wheel to the axle in conventional cars. Instead, the Pursuit uses electric wiring linked to sensors that relay the car's speed and steering-wheel angle to an electronic control module.

The control module uses the sensor information to determine how much each set of the Pursuit's wheels should turn and in which direction they should turn.

Electronics are also playing a role in some of the new four-wheel-steering systems and the improvements in four-wheel drive.

Four-wheel drive supplies power to all wheels of a car. The objective is to increase on-the-road traction in inclement weather. Four-wheel-drive vehicles designed for off-road use pack an extra punch -- the ability to move through grass, mud, sand and fordable streams, and over rocks with relative ease.

Four-wheel steering's purpose is to improve vehicle handling on the highway and maneuverability on the parking lot.

Examples: At highway speeds, the rear wheels of a four-wheel-steer car turn in the same direction as the front wheels. The aim is to give the car greater stability during risky, high-speed moves, such as cornering and changing lanes.

In low-speed maneuvers, such as parallel parking, the four-wheel-steer system moves the rear wheels in a direction opposite from that of the front wheels. The purpose is to give the car better movement in tight-space situations, thereby reducing chances for nuisance accidents that can cause dents and scratches.

Four-wheel steer and four-wheel drive are not new in the generic sense. For example, some four-wheel-steer military vehicles were in use in World War I, and four-wheel-drive Jeeps became legendary in World War II.

What is new is the zeal of most of the car makers in updating and refining the systems, and their aggressiveness in bringing the technology to market, said Thomas O'Grady, president of Integrated Automotive Resources in Wayne, Pa.

"Four-wheel steer," for example, "will be a winner" with consumers, said O'Grady, an auto industry consultant. But because the system will be offered on a limited basis in the 1988-model year, "it will not shake up the market" in its first season, he said.

But that is okay, because Honda, Mazda and Nissan primarily are trying to burnish their reputation for technological leadership with their early introductions of four-wheel-steer systems, O'Grady said.

"They will be sending a signal to consumers that says: 'Here are the Japanese coming in here again with the latest technology, while the Americans are still waiting in the wings trying to figure things out,' " O'Grady said.

If four-wheel steer catches on with consumers and becomes identified as a "Japanese invention," it will add luster to the high-quality image Japanese car companies already enjoy in the United States, said Dennis Virag, vice president and general manager of Automotive Consulting Group Inc. in Ann Arbor, Mich.

U.S. car companies can ill afford to let the Japanese win that kind of public relations battle, but at the moment American car companies are showing little interest in four-wheel steer, Virag said.

Instead, U.S. auto makers are trying to produce more sophisticated four-wheel-drive vehicles, a market segment in which the Japanese and Europeans are fierce competitors.

But to many of the nation's auto dealers, that U.S. tack is pretty smart.

Sales of four-wheel-drive vehicles, both cars and light trucks, are growing rapidly, according to the latest available figures compiled by the McLean-based National Automobile Dealers Association. The group represents nearly 20,000 of America's estimated 25,000 franchised new-car dealers.

Fewer than 160,000 four-wheel-drive vehicles were sold in the United States in 1965, compared with nearly 1.2 million in 1985, NADA officials said. "The popularity of four-wheel-drive vehicles indicates that a continuation, or perhaps an acceleration, of this trend is likely," said NADA spokesman Lou Priebe.

Older four-wheel-drive systems were cumbersome to use, requiring the driver to shift a lever on a transfer case and, in some cases, get out and lock the hubs on the front wheels. In addition, these systems were restricted to slippery conditions. Lacking internal flexibility, they caused excessive wear on tires and drive train if employed on dry pavement.

Newer four-wheel-drive systems, such as those on some Ford Motor Co. Topaz cars, can be activated at the flip of a dashboard switch.

Other types, like those in some Honda Civic wagons, are meant to be "on" all the time, operating as two-wheel drives until there is traction lost at the drive wheels. The computerized Honda system senses the wheel spin that accompanies traction loss and automatically engages the other wheels to increase traction on slippery surfaces.

GM's Dickinson agrees that his company is paying more attention to four-wheel drive than four-wheel steer. There is a demonstrated market demand for four-wheel drive, and the consumer benefits and reliability of four-wheel-drive systems also are well-established, Dickinson said.

Four-wheel steer is a different story, said Dickinson, echoing sentiments expressed by other domestic auto makers.

"Four-wheel steer has some very interesting handling characteristics. But I'm not sure of the overall technical benefits of this system, or of the overall benefits for the customer," Dickinson said.

A four-wheel-steer system can add from $500 to $800 to the price of a car, depending on the type of car and the sophistication of the system installed, according to some industry reports. Any auto maker asking customers to pay that price for an option ought to be certain of its value, Dickinson said.

Anyway, said Dickinson, GM "for years has had a compliance steering system that gives our cars as good or better handling than any other comparable cars in the world."

In compliance steering, a car's rear wheels have some built-in "give," allowing them to twist one degree in turns, thereby reducing the tendency of the car's rear end to swing out in curves, Dickinson said.

GM has been working on four-wheel-steer concepts for over 20 years. But the company's officials "will wait until we have a clearer understanding" of the system's potential problems and consumer acceptability "before we go to mass production," Dickinson said.

O'Grady said GM and like-minded domestic auto makers could be taking a risk with their "wait-and-see" attitude on four-wheel steer.

Car companies in the past could afford to allow competitors to take the risks of product development and then, depending on consumer acceptance, follow with similar products of their own.

"But all of that's changed today," said O'Grady. "Things are moving too fast to play follow-up. By the time you let someone develop a new product and test it for market acceptability, the market has changed."