Where Ohno saw flow and heartbeat, the Americans saw speed and volume. They saw that the faster they could ‘push’ work through the lines and the greater numbers of cars they made, the more cheaply and profitably they could do so: the greater the economies of scale. This approach was an extraordinary advance on previous manufacturing methods and was remarkably successful provided that buyers accepted they could have any colour so long as it was black. In little time, however, consumers wanted variety, and it was the need to produce variety that threw into sharp relief the limits of the American paradigm. The American approach to variety was to produce different models in batches that were as large as possible to maintain economies of scale. To do this they needed to