'"The Motor Girls" is a series of young adult novels written by Margaret Penrose in the early 20th century. The series follows a group of teenage girls who form a motor club and embark on exciting adventures together. Throughout the series, free friends are trying to solve mysteries, help people in need, and take on daring challenges while driving their cars. The books were popular in their time because they offered young girls a sense of independence and adventure, which was unusual for female characters in literature at the time. They also provided a window into the early days of the automobile industry and the culture surrounding it. Although the series is somewhat dated by modern standards, it remains a beloved classic among those who enjoy vintage children's literature and early 20th-century Americana.