This 1955 Pontiac Star Chief arrived the same year Pontiac retired its straight-eight engine for good, replacing it with the new Strato Streak V8 that would define the brand for the next two decades. Wrapped in twin Silver Streak hood trim and a light-up Indian-head ornament, it was also a genuine volume seller, with Pontiac building over 200,000 of them that year alone. Here’s the story behind the engine switch that reshaped Pontiac’s flagship.