With its custom red paint job, on-board TV, public-address system, game consoles and sparkling chrome tire rims, the 2003 Hummer was no ordinary vehicle. The $45,196 SUV was designed to deliver an eye-catching, AIDS-awareness message to people in poor African-American neighborhoods on behalf of the Illinois Department of Public Health, then headed by Dr. Eric E. Whitaker, one of President Barack Obama’s closest friends.Soon, though, other AIDS activists began to question how the Chicago not-for-profit organization that used the decked-out Hummer to spread its message could afford to spend money on such a vehicle. After first insisting otherwise, Whitaker aides...