“â€œHappy Birthday, Tin Lizzie! Letâ€™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. â€œYou 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.