Better oversight of the U.S. Postal Service's fleet could allow it to pocket $17 million in savings, the agency's inspector general found.

The Postal Service's transportation and delivery fleet includes more than 215,000 vehicles, worth around $3.5 billion. However, in six Washington-area districts and two West Coast districts, the Postal Service slacks on vehicle maintenance.

Missing maintenance times, performing unnecessary checkups and hiring outside labor cost the Postal Service more than $17 million, the inspector general discovered.

The Washington-area districts include the District of Columbia, Baltimore and Northern Virginia.

Unscheduled maintenance, for example, cost the Postal Service $12,967,556 — $3 million more than what the agency aimed to spend.

When hiring outside work for maintenance and vehicle repairs, the Postal Service spent $8.1 million versus the $4.3 million it would have spent with agency workers.

The IG's office found numerous conditions contributing to the inefficient work, including performance indicators that have not been updated since 1996 and vehicles so old they demand more maintenance and repair.

The IG recommended to fill vacant positions and have a maintenance structure in place — something the Postal Service agreed to do.