THE 1986 Buick Riviera. General Motors thinks it's "the most technologically sophisticated car available" in the United States this year. And GM may be right.

Certainly, no other car boasts a touch- sensitive video screen that controls and monitors most of its basic functions.

The screen, actually a three-by-five-inch cathode ray tube, sits a little to the right of the driver. Touch it to adjust the cabin temperature of the car. Touch it to turn on the radio, adjust its volume, change its stations. Touch it to get information on engine functions, distance traveled, elapsed time since departure.

You reach out and touch so much in this car, you wonder if it was actually designed by AT&T.

But all of the touching is appropriate, considering the Riviera's interior.

Talk about revamped cush! Velour, velour everywhere -- on pillars and posts, seats and dash. Black cherry. Monocoque design. Plush.

Still, this is a classy job, devoid of the boisterous exhibitionism that often masquerades as luxury in domestic automobiles. You can take this car to the club.

Outstanding concern: Can something as sophisticated as the Riviera's Graphic Control Center, the proper name of its touchy-feely screen, function reliably longterm?

GM engineers say that the control center is durable, and is no more prone to breakdowns than more traditional instrument panels. But some GM dealers say privately that their service people now lack the necessary training to repair these devices properly.

Said one dealer: "They're giving us cars designed by engineers from MIT, and they want us to repair them using people with high school diplomas."

Outstanding praise: A simply beautiful machine in both form and function. At 187.2 inches, the 1986 Riviera is 19 inches shorter than its 1985 predecessor; and at a base weight of 3,309 pounds, it is more than 500 pounds lighter. But it retains all of the character of its foreunner.

This is a road car, a good one.

Ride, acceleration, handling: Remarkably smooth in all three categories. The Riviera's 3.8-liter, V-6, fuel-injected engine delivers power without vibration or hesitation. Acceleration is so quiet and quick, you really must pay close attention to the speedometer.

Head-turning-quotient: The Riviera got raves, even from import devotees. People actually stopped to touch this car, literally to run their fingers along its sleek, flowing, Avanti- like lines.

Sound system: AM/FM stereo cassette with graphic equalizer, GM's top-of-the-line Delco/Bose version. Truly exceptional. If you can find a better system, and can afford it, you really ought to buy it.

Mileage: About 28 to the gallon, mostly at constant highway speeds, running driver only and with winter climate-control system operating.

Price-as-tested: $22,907, including $3,076 in options, among them the Delco/Bose stereo for $895 and the Lear seats at $947. In addition, you should expect a $500 destination charge. Ah, beauty and the beast.