The choice of engine technology for the automobile is currently at issue, but not for the first time. When the automobile was introduced to the United States in 1895, it was not apparent what engine technology would prevail. Steam, electric, and internal combustion engines all had their own merits. But within a few years internal combustion had eclipsed its rivals to become the single commercially viable engine technology. Many factors that affected the choice of internal combustion have been noted in the literature and in the popular press; here a model integrates all these factors into a single comprehensive framework. The critical years when the technology choice occurred are pinpointed, and a new, comprehensive framework is used to identify the key factors that determined the choice.