Got that nagging feeling you've forgotten something in 1985? Did you set up an IRA? Buy Aunt Edna a Christmas present?

What about the car? Did you forget this was also the centennial of the automobile, that marvelous machine you've lived in, loved in, lingered in and left in?

It's one event you can still catch up on. Bring the roadster into the garage, wax it up, and reflect on where you'd be without it: poorer, dumber and much more boring. Fun for the Whole Family

Back when the newfangled automobile was a fearsome thing, a law was proposed demanding that self-propelled vehicles come to a complete halt at all intersections. After doing so, "the engineer must thoroughly examine the roadway ahead and sound his horn vigorously. Then halloo loudly or ring a gong . . . discharge a Roman candle, Vesuvius bomb or some other explosive device as final warning of his approach."

That ought to keep the corner of Wisconsin and M hopping. Accidents Will Happen

It was Karl Benz, a German mechanical engineer, who built the first successful gasoline-powered vehicle. His 1885 contraption resembled a giant baby carriage; it completed four laps around the factory before it broke.

Several weeks later, Benz was demonstrating an improved model when he achieved another breakthrough: the first automobile accident. Apparently, he was so thrilled by his car's performance that he forgot to steer it and ran into a brick wall. Parking and Sparking

Early automobiles not only provided courting couples with an escape from watchful parents, they offered a destination as well -- when you got away, you were already there.

"Cars were seen then as much more innocent," says David L. Lewis, author of the classic study, Sex and the Automobile: From Rumble Seats to Rockin' Vans. "If you were going to a motel, you were going there for one reason. In a car, the question was open. Many couples went out in cars not expecting to do anything, but ending up doing something anyway."

Lewis, a professor of business history at the University of Michigan, has researched this subject for more than 25 years. He takes it quite seriously: "Sex in cars is often ridiculed, but many people have told me that it's different, exciting . . . It adds another dimension."

Sex in cars has been going on since the '20s, reaching its heyday in the late '50s and early '60s. The energy crunch produced a size crunch, and the downsizing of cars gave people less headroom, legroom and, well, not enough room.

"All but the most acrobatic have trouble managing things in cars these days," says Lewis. Only 7 percent of couples, he reports, now make love in cars. Oops, I Thought This Was the Bank

The Pointe Coupee Funeral Home in New Roads, La., is like any other -- except for its drive-up window for viewing the deceased.

"We have a lot of people who wanted to view the body before the wake hours -- handicapped people who couldn't easily get inside, schoolchildren, working people who didn't have time to dress up. So we came up with this," says Irma J. Verrette, whose husband, Elijah, started the window in 1973.

The window's a hit, she says; 80 to 90 percent of the families request it. "People can pass by in their cars, sign the register, and the family would know that they did care. It has taken very well."

It's also an innovation in the best Detroit tradition. Says Verrette: "You sit down and try to inject something new every once in a while to keep your business going." There Goes the Neighborhood

The automobile didn't create the suburbs, but it shaped a good deal of suburban life, from the drive-in movie theater and the shopping center to the primacy of the garage.

"The car breaks our connection with the central city. With streetcars, there were still suburbs, but the streetcar went in only two directions: toward the city and further out into the country," says Columbia University historian Kenneth Jackson.

"Not only does the car not force you to go downtown, it actually discourages you from it, with congested traffic, high parking costs and so on. The car encourages you to go off in different directions."

But if the car provides a broader choice of stores and entertainment, it also dislocates a community.

Before the car, Jackson points out, people lived closer together, and they frequently traveled on foot. Pedestrians made the streets lively, and a good deal of social interaction took place on the front porch or stoop.

"If you sat on the front porch now, you wouldn't see anything -- a jogger, maybe," says Jackson, who lives in suburban Westchester County, New York. "If the automobile raises the scale of life, it also destroys any sense of neighborhood." The Democrats: A Breed Apart

By permitting more cross-breeding, the automobile has long been considered responsible for improving the American species. The horse and buggy gave people a courting range of five miles; the car, 50. Automotive historian David L. Cohn noted in 1944 that the car was improving the breed of southeastern Democrats.

Previously, suitors "took the first girl within reach of their horse and buggy, and since their ancestors had been doing this for decades, inbreeding had produced a large tribe of authentic and picturesque idiots, some of whom would inevitably turn up in Washington as legislators."

With a car, however, a man could go far enough afield so his bride would be no closer relation than a third cousin, said Cohn, and "thus the Democrats at one stroke would maintain their birth rate and improve their breed." Driving Them Crazy

If you've ever been stuck on the New Jersey Turnpike in front of a truck driver who leans on his horn and switches on his brights because your Toyota's in his way, you know that being afraid to drive is sometimes the only sane reaction.

When psychiatrist Roy Mathews studied driving phobias in Houston -- a city with minimal public transportation -- he was surprised by the response.

"I didn't think the fear was so widespread, but the incidence is very high," says Mathews. "While some driving anxiety is justified, with these patients it was . . . in excess of what could be described as reasonable."

The victims of the phobia would live their lives around it. Some would stay home until the morning rush hour was over, and then stay at work until the evening rush had finished. Others were totally housebound, and would leave their houses only on foot.

"The fear is irrational, but they were not able to overcome it -- and when these people try to force themselves to drive, they can become a source of danger," says Mathews. "It's a condition that is likely to get worse." Handling the Neigh-Sayers

Horses were easily spooked by the noisy new mode of transportation. The simple solution offered by Uriah Smith of Battle Creek, Mich.: Make cars look like horses. A false front in the shape of a horse's head and neck would be put on each automobile. Whenever the false horse met a real one, there would be only contented whinnying. Why You Shouldn't Move to L.A.

The smiling visage of Lee Iacocca to the contrary, the boom days for the automobile are over. Output is expected to be stagnant over the next several years, followed by a fairly sustained decline in production in the 1990s. The cause: a tightening oil supply.

"Some American cities are going to be well-equipped to handle that adjustment," says Les Brown, president of the Worldwatch Institute. "Washington, for example, now has in place a transit system that could keep the city working well even if the number of automobiles were cut in half."

The cities that would be affected most, he says, are those that have grown up recently and have a high commuting cost -- Los Angeles, Houston, Dallas.

"We'll probably see rationing systems," Brown says. "By 2000, I would not be surprised to see the price of gas nearly double what it is now." Trafficking in Romance

"I had had it with singles clubs and magazines," says Huntington Beach, Calif., widow Ruth Guillou. "People would say they were tall and handsome, and I'd go meet them, and they were the complete opposite. I'd say 'Excuse me,' go to the ladies' room, and never come back."

So when Guillou, a real estate agent in her fifties, stopped at a traffic light and flirted with "a charming gentleman in a cream-colored Cadillac," she was ready for a new method of dating.

That man got away, but Guillou saw the idea for the Freeway Singles Club. Members put a decal on their windows and contact each other through the club. There are now chapters in 38 states, including Maryland and the District.

"People are getting tired of the bar scene, and it's dangerous. You don't know if someone's married or not," says Guillou, who drives a Mercedes-Benz.

Finding the perfect mate, however, is not guaranteed.

"I've met a few men since then," Guillou says, "but I'm still looking for the one in the Cadillac."