Rasheim Lewis, 32, of Danbury, was the only occupant of the Honda, which was "attempting to elude" the Monroe Police Department on the northbound side of South Main Street/Route 25, state police said.
Monroe Police were attempting to stop the 2000 Honda Civic, which had been reported stolen out of Danbury on Monday, according to state police.
The crash occurred in the vicinity of Sand Hill Plaza just after 9 p.m. Tuesday, state police said.
Lewis was taken to Danbury Hospital with serious injuries. The driver of the Mercedes, a 46-year-old Newtown woman, declined transport to the hospital, state police said.
South Main Street/Route 25 was closed for hours overnight but reopened for the Wednesday morning commute.
Connecticut State Police took over the investigation at the request of the Newtown police. The Danbury state's attorney's office has been notified.
Anyone who witnessed the crash is asked to contact State Trooper Mark DiCocco at 203-630-8079.
Click here to follow Daily Voice Newtown and receive free news updates.