““Happy Birthday, Tin Lizzie! Let’s go!â€ン shouts Grandpa as his one-hundred-year-old car explodes into life. The children jump aboard the vintage Model T Ford that they have helped him to restore, and a celebration road trip begins. “You gotta have wheels!â€ン Grandpa cries. But as traffic jams build, the children begin to ask serious questions about cars and the problems that have developed: overcrowded roads, pollution, and oil-dependency.