20 cars on a 7×9 lot. 55 seconds on the clock.
20 cars left
You have 55 seconds, starting at your first tap. A bump costs 3 seconds.
Drive the cars out in this order: 2, 1, 3, 5, 4, 10, 11, 14, 15, 17, 13, 8, 7, 6, 18, 19, 20, 9, 16, 12.