Found this at B&N : At Every Turn by Anne Mateer
She's off to the races!
Caught up in a whirlwind of religious enthusiasm, Alyce Benson impetuously pledges three thousand dollars to mission work in Africa. Now she just has to find a way to get the money.
Alyce harbors a secret passion for speed and automobiles, and she's spent many an afternoon driving around the rustic track in the field behind her home. When she discovers that her father's company has sponsored a racing car that will compete in several upcoming events--races in which the driver will be paid and could win as much as five thousand dollars in prize money--she conspires with her father's mechanic, Webster, to train and compete.
But when her friends cast aspersions on Webster's past, she realizes she may have trusted the wrong person with her secret. Will Alyce come up with the money in time, or will she have to choose between her hasty promise and the man who holds a piece of her heart?