In a hurry? Late for an appointment? Want to get a head start?

Cleveland T. Tucker of Dinwiddie, Va., has just the thing for you. The 37-year-old inventor has designed a device to start your car by simply opening the door. Tucker hopes to market his idea to law enforcement agencies and fire departments, but since he received his patent in September has had no takers.

It could also be used, he acknowledges, in a getaway car. "Many people think about it that way," he said, "but all the time I've had it, I haven't robbed no bank or no store." Criminals will be criminals in any case, he said.

Tucker was among 70 inventors whose ideas were on display yesterday at the 10th annual Inventors Day at the U.S. Patent & Trademark Office in Crystal City. His maroon and black 1970 Impala was parked outside the exhibition hall that contained what their creators characterized as the solutions to some of the oldest and most intractable problems known to man.

Cures for the human ills of crime, ignorance, disease and boredom, as well as novel ways to solve the energy crisis and the transportation needs of society were all on display during the two-day show that ended yesterday. These included solar heating systems, chin-operated wheelchairs, and Ernest E. Grimsley's portable machine for boring and facing ball valves, which has been successfully marketed to the federal government and to private industry.

"Yankee ingenuity" is what Commerce Secretary Malcolm Baldrige called it during remarks delivered before the bestowing of awards and honors and a film about Henry Ford. The $1,000 prize for inventor of the year went to Don Ausmus, of Independence, Mo., who designed a wheeled, motorized vehicle for paraplegics like himself.The annual show is held to encourage and display the ingenious achievements of American inventors.

Baldrige said inventions were needed "now more than ever" to produce "jobs, jobs, jobs." But some of those on display were mainly for fun.

"This will put you in the nut house. It's worse than the Rubik's cube," said Kevin Hines, 12, of McLean, as he struggled to master "The Geosphere," a 180-piece three-dimensional puzzle patented by Roger M. Stolpin, of Holly, Mich. The dome-shaped "topological puzzle" is 28 inches in diameter and sells for $39.95. So far, sales have been slow, its inventor said.

Stolpin's wife is less than enthusiastic. "I've learned to live with it," she said. "Let me put it this way, there's one hanging in my living room."

For the young and the old alike, William J. Quemore Sr., 85, said he had just the thing, a "Knobby Knob" attachment for a guitar which allows anyone to play three standard chords without actually fingering the frets. The inventor from Blackwood, N.J., said he plans to put his family to work making the item, which sells for $10 but has yet to catch on with the public.

Roy Boland, 54, of Claymont, Del., didn't start out to invent a toy, but so far the best response to his "contractible" monorail car--designed to be raised and lowered by hydraulic arms to and from its overhead support--has come from children. "I made the model over the Christmas holidays," he said of his first and only invention. "I wanted to make my debut here."

His monorail car was designed exclusively for police patrol work in the city, he said, "but I'm gonna try to interest some toy manufacturers at first."

Nearby, David Kerber, 40, of New York City said he had the "greatest invention of all time" in his "Towline Transit" patented last May. "No one's built it, no, no one's bought it," he said of his cable car system, designed to move people in 50 "cabins" among 50 stations on a 10-mile loop. "I'm here to market it," he said.

For others whose favored mode of transportation is solo flying, Igor Dmitrowsky, also from New York, offered the "homo-avis," a single-engine wing "attachable to the body of a pilot." A more advanced twin-engine model, "The Commando," is currently being built, he said.

Tom Sutor of Atlanta, a member of the Inventor Associates of Georgia and a former Navy pilot, was openly skeptical of the machine's ability to land its operator in one piece. "Have you tried it?" he asked the promoter. "Well," replied Dmitrowsky, "according to our calculations . . . . "

If many of the inventions seemed offbeat, they were. "They have to be unusual," explained William Feldman, deputy assistant commissioner for patents. "That's why they're inventions."