Fairfax County, a suburb with a lifeline to the automobile, appears to be bloated with unnecessary cars for its government workers.

That's the conclusion of the county auditor, who was prodded to investigate the government motor pool after he was shocked one day by the large number of official vehicles parked in the garage of the Herrity Building, where he works. Auditor John Adair's report, showing one car for every three employees, caught the eye of Board of Supervisors Chairman Gerald E. Connolly (D), who saw a way to save millions of dollars a year in maintenance and purchase costs by shrinking the fleet.

"There's been an institutional inertia that says once you get a vehicle, it's forever," Connolly said. "Frankly, what we've had is a sloppy system that discouraged people from giving up the vehicles they don't need."

As the board looks to trim the property tax rate and curb rising real estate taxes, any savings in maintaining the fleet "may not be a huge savings, but every little bit helps," he said. Each vehicle costs about $20,000 to maintain over a six-year life cycle, then about $15,000 to replace, officials said.

In recent years, the county's fleet costs have jumped by millions of dollars, from $41 million two years ago to $52 million in the current fiscal year. Officials blame higher gas costs and payments to a replacement fund that acts as a savings account to cover the cost of new cars and trucks.

Fairfax maintains about 5,800 vehicles for use by county agencies -- including 2,173 for the school system, 1,150 for the police department and 400 for the fire department. Tractors, bulldozers and other heavy equipment account for much of the rest.

Hundreds more are passenger cars -- sedans, including Fords and Dodges -- for employees to drive throughout the county for meetings, site visits and other business. Social workers visiting foster children, tax assessors and building inspectors are encouraged to use county cars rather than be reimbursed mileage costs for using their own cars. The county has 11,500 employees, excluding school employees.

The District, by contrast, maintains 5,000 vehicles for a workforce of 32,000, including public safety and school vehicles. "But we have Metro and a better taxi system," said Public Works Director William O. Howland Jr., who oversees the fleet. Montgomery County keeps 3,000 vehicles for 7,500 non-school county workers; the fleet does not include school vehicles.

About 160 of the Fairfax cars are taken home by county employees, many of them police, fire officials and others who can be called to emergencies at any hour. The county clamped down on the take-home fleet during the recession of the early 1990s, as the supervisors squeezed perks before resorting to more painful cuts.

Fairfax is a big place, spanning 399 square miles. Employees use county cars even if they are traveling to a meeting four miles away. Still, more than 400 vehicles in the fleet were driven fewer than 4,000 miles in 2003, Adair found -- too few to justify having the cars, which are replaced on a regular cycle anyway.

Jim Gorby, the county's director of vehicle services, acknowledged that the fleet could be pruned. But he said that providing a car for county business is for many workers what a desktop computer or cell phone is for others.

"A vehicle is a tool for getting your job done quicker, more efficiently or more times a day," Gorby said. "It's an adjunct to the staff person."

Fairfax is following the lead of Virginia and some federal agencies that have moved this year to save money on cars. A report in May by the Government Accountability Office found that some federal agencies could not justify many of the 387,000 vehicles surveyed against the driving requirements of their jobs. A report by the Richmond-based Joint Legislative Audit and Review Commission, the General Assembly's watchdog, drew similar conclusions about the state fleet.

Government passenger cars can be signs of excess to taxpayers, who see license tags with "Official Use Only" and, in Fairfax's case, the county seal on the sedans' side doors. Gorby said his office receives several complaints a week from the public about personal use of the vehicles.

Employees can stop for lunch "and those types of things," he said. "We have no problem at all with citizens coming in and telling us whether someone cut them off or was speeding or showed up somewhere not on county business." But he said abuse is minimal.

Asked this fall to give up cars voluntarily, county agencies turned in 44 vehicles, Gorby said. Officials plan to take a much harder line to find more savings and have formed a committee to investigate vehicle assignments and usage.

The annual mileage threshold below which a car's use will not in most cases be justified has been increased from 4,000 to 5,000. That's lower than the state standard of 7,000 miles for compact sedans, 8,571 miles for mid-size sedans and 10,851 for full-size minivans.

The Fairfax committee is considering whether some cars assigned to individual employees should be transferred to a county pool or whether reimbursing for mileage, which is done for some workers, would be more efficient. It's unclear how many cars will be cut from the fleet.

Gorby pointed to problems with both approaches. "A vehicle is cheap compared to having an hour a day lost while someone tries to find a car in the motor pool," he said. He also predicted that employees' insurance companies would increase rates when policyholders say they are using their private cars for business.