At least according to author Matthew B. Crawford, Henry Ford did not raise wages out of the goodness of his heart, so his workers could afford to buy cars themselves.
From his original Shop Class as Soulcraft essay:
http://www.thenewatlantis.com/publications/shop-class-as-sou...
"Given their likely acquaintance with such a cognitively rich world of work, it is hardly surprising that when Henry Ford introduced the assembly line in 1913, workers simply walked out. One of Ford’s biographers wrote, “So great was labor’s distaste for the new machine system that toward the close of 1913 every time the company wanted to add 100 men to its factory personnel, it was necessary to hire 963.”
This would seem to be a crucial moment in the history of political economy. Evidently, the new system provoked natural revulsion. Yet, at some point, workers became habituated to it. How did this happen? One might be tempted to inquire in a typological mode: What sort of men were these first, the 100 out of 963 who stuck it out on the new assembly line? Perhaps it was the men who felt less revulsion because they had less pride in their own powers, and were therefore more tractable. Less republican, we might say. But if there was initially such a self-selection process, it quickly gave way to something less deliberate, more systemic.
In a temporary suspension of the Taylorist logic, Ford was forced to double the daily wage of his workers to keep the line staffed. As Braverman writes, this “opened up new possibilities for the intensification of labor within the plants, where workers were now anxious to keep their jobs.” These anxious workers were more productive. Indeed, Ford himself later recognized his wage increase as “one of the finest cost-cutting moves we ever made,” as he was able to double, and then triple, the rate at which cars were assembled by simply speeding up the conveyors. By doing so he destroyed his competitors, and thereby destroyed the possibility of an alternative way of working. (It also removed the wage pressure that comes from the existence of more enjoyable jobs.) At the Columbian World Expo held in Chicago in 1893, no fewer than seven large-scale carriage builders from Cincinnati alone presented their wares. Adopting Ford’s methods, the industry would soon be reduced to the Big Three. So workers eventually became habituated to the abstraction of the assembly line. Evidently, it inspires revulsion only if one is acquainted with more satisfying modes of work."
I think every worker in America should read Crawford's superb book, btw.