The car was found on Saturday near Harrison and Western.
Family members believe that Saucedo was killed elsewhere, his body then stuffed in his car and left on the street. He had been missing since early last week.
Relatives live on both floors of the two buildings next door to each other in the South Side neighborhood. They say it was a perfect situation for Saucedo because family was his top priority.
"He loved his daughters very much," said Cherise Lile, Suacedo's neice. "He was all about his sisters and brothers, very family oriented and this is just devastating to the family. I know that it's killing all of them."
The 59-year-old Saucedo was born in Mexico but has lived in Chicago most of his life. He sold jewelry at flea markets and out of his home.
Police suspect robbery was the motive. His home was ransacked and his car stolen. Left just a block from the Eisenhower Expressway near Western.
On Saturday evening, police found the car and discovered what relatives believe was Saucedo's body, badly decomposed in the trunk.
"Everybody's really distraught," Lile said. "It just doesn't seem real. We were actually hoping he would just show up and yell at us for being here, wondering why we were here."
Neighbors say they are worried about apparent random violence here. They say Saucedo had no enemies.
"I come home from work and I see a lot of police around," said neighbor Jose Nabjas. "His nephew told me what happened and feel bad because he was a good guy, a good neighbor."
The medical examiner did an autopsy Sunday, however the office is not ready to release a positive identification until they are able to go through some dental records.
Family members in Mexico are en route to Chicago.