Police found the body while responding to a report of an automobile crash, the Chicago Sun-Times reported.
The woman was pronounced dead at Northwestern Memorial Hospital, the Illinois State Police said. A second woman in the van was not injured.
Police said the 32-year-old woman was fatally shot when a van pulled alongside her vehicle and fired 10 to 14 shots, the Chicago Tribune reported.
One round hit the woman, who was driving.
Police said the shooting may have been drug-related. The van was discovered about 4:20 a.m.