Rev. W. Awdry 
Thomas and Friends: May the Best Engine Win (Thomas & Friends) 

EMILY, THE NEWEST engine, is determined to prove that she is as Really Useful as Thomas, so she challenges Thomas to a race: whoever can do the job the fastest is the winner. Soon they are off, each on a whirlwind rush around the Island of Sodor. But they both realize that speed is only part of being Really Useful . . . the work must be done right.From the Hardcover edition.