The woman, in her 30s, and the child were abducted two men in Redcar, Teesside, at lunchtime on Friday.
They were taken about four miles to Longbeck Lane, near Yearby, where the woman was raped. They were made to get out of the car six hours later in another area of Redcar.
Police are investigating whether the attackers knew the victim.
Temporary Det Ch Insp Matt Murphy-King said it had been a "very traumatic ordeal for the victim and her child".
"Although we are investigating that the attackers may have known the victim, as a precaution I would encourage anyone in the local area to be extra vigilant," he said.
"There are a team of detectives working on this investigation and we have increased patrols in the local area."
Cleveland Police want to speak to anyone who saw a woman with a child and "in a distressed state" running across the road towards a wooded area near Kirkleatham Lane, where she got out of the car.
The force is also appealing for information about the two men in a dark-coloured saloon.
The driver, in his late 20s or early 30s, was white, with short, brown hair and a large build, police said. He had the word "love" tattooed across his knuckles.
The other man was white, in his early 20s, of shorter height and medium build, with brown hair.
A woman was raped in the middle of the day after being forced into a car with her toddler as they walked by the sea.