The District is potentially on the hook for more than $33,000 to cover the cost of two Lincoln Navigators leased at the request of D.C. Council Chairman Kwame Brown, who drove one of them for month before both were returned. The biggest chunk of change comes from an illegal $17,600 prepayment on the first Navigator leased at Brown’s request the day after the general election in November, Department of Public Works Director William Howland testified Thursday during a D.C. Council hearing called by Ward 6 Councilman Tommy Wells to investigate the city’s vehicle procurement system. That illegal prepayment was the second in five years made for a council chairman’s ride, Howland said. In 2006, the city leased a Chevrolet Tahoe at then-council Chairman Vincent Gray’s request and illegally prepaid all four years of the chairman’s lease. As mayor, Gray now rides in a fully-loaded Navigator requested by the police department.