Police said the suspect, Evan C. Gregory, 41, of Santa Rosa, was trying to sell the Mercedes at a gas station at Casa Grande Road and Lakeville Highway around 11 p.m., police said.
Someone found his behavior suspicious and called police, who responded and determined that the car had been stolen from Santa Rosa.
Gregory left the scene before police arrived. He later returned without the car but had the keys on him, police said.
He was detained, and the stolen car was found parked in the 5900 block of Lakeville Highway.
Gregory was also found with mail stolen from the same area in Santa Rosa the car had been taken from, police said.
He was booked into Sonoma County Jail on charges of vehicle theft and possession of stolen property.