Here Lies the Librarian by Richard Peck

From Menasha Kids Bibliopile:
Peewee lives with her brother Jake in rural Indiana where they are trying to make a living at running a garage. But it is 1914, and the automobile is just starting out. To add to their troubles, their competitors who live in town are willing to damage people's cars for business and to rob others. Everything changes when a tornado rips through the community, damaging the library that has been closed for years. Four female library students who also drive cars arrive in town to be the librarians. Peewee has suddenly found role models for being a lady. But sometimes Peewee finds herself sitting on the sidelines when she would rather be in the race. Can a young lady do both?