Rat Race: Journey of Hope by Tiffany Robinson

Adventures await, but the Legends racing team has a big problem. They’re running out of money, and there's only one way to fix it—win a million dollars in the 'Round the World Race. But there's one huge obstacle: they can't find enough racers. Rexie Rat volunteers, but Big Rex won't even consider it. Rexie is determined to prove she's ready to race, no matter what it takes. Even worse, the other team members have troubles of their own that no one knows about—yet. Can Rexie convince her father that she's good enough to compete? Will she be there for the team when they need her most?