The State of Virginia spent $5 million to erect a three-story, 352-car garage over I-66 in Arlington that sometimes is filled with more teen-age lovers from a nearby high school and abandoned refrigerators than cars.

"It's way underutilized," said Dennis Johnson, chief of Arlington's public works operations division. He said he has counted anywere from none to five to 45 cars parked during the day in the cream-colored garage, at North Quincy and 15th streets near Washington-Lee High School and county school administration offices.

Other officials put the number of cars using the garage slightly higher but acknowledge it's well below their projections. Open just a year, the garage was built by the Virginia Department of Highways and Transportation to compensate Arlington for the loss of parking spaces to I-66.

Although the garage is open free to anyone at any hour of the day or night, few seem anxious to use it.

"We're in kind of a curious predicament," said C. Thomas Weber, the county official in charge of the garage. "We can't advertise the free parking.

"We have to use word of mouth," he said, because Arlington doesn't want to appear to "be in competition with the people who sponsor us," the tax-paying businesses, which run profit-making garages around the Parkington Shopping Center and Ballston Metrorail station to the south.

When the garage was planned, officials expected Washington-Lee students, teachers and school administrators would use the garage frequently. One school day last week, however, only a few young hand-holding couples could be found in the shadows of the middle deck amidst five cars.

"We've had a couple of cars abandoned in there," Weber said. "And we've had people dump trash and discard stoves and refrigerators."

A six-block walk from the Ballston Metro station and a slightly longer distance to the Virginia Square Metro stop, the garage could be used by Washington-bound commuters or people wanting to use the 15th Street nature park or two basketball courts that soon will be lighted on part of the upper deck.

"The only time it was full that I can recall was when we had a graduation," Weber said.

Officials once considered charging for parking, Weber said, but they scrapped the plan after the county attorney's office said the garage could not make a profit.

"It didn't make any sense to charge if we could only get to the break-even point," he said. The schools pay a custodian $17,000 a year to maintain the garage and the education center grounds.

While the garage sits virtually unused, another state highway project on I-66--an urban park atop the interstate at Rosslyn Circle--remains unfinished for lack of funds.

Why was the garage built before the Rosslyn park that county officials have been scrambling for? Jack Hodge, assistant chief engineer for the state highway department, said state highway funds were more plentiful when the garage was built.

"We had to fund the project as we went along. . . . Our top priority was to get the road open and the second priority was to get the plaza done, realizing it is a gateway to Virginia."