21 cars on a 7×9 lot. 60 seconds on the clock.
21 cars left
You have 60 seconds, starting at your first tap. A bump costs 3 seconds.
Drive the cars out in this order: 1, 2, 3, 5, 6, 7, 9, 10, 11, 13, 14, 16, 17, 8, 4, 12, 15, 19, 20, 18, 21.