The Pontiac GTO ushered in the era of the American muscle car in the 1960s, just as baby boomers began to come of age. The 1966 model (the &#34;Goat&#34;) featured curvy Coke-bottle styling and could really move, going from 0 to 60 miles per hour in 6.8 seconds. In 2013, the GTO will roar in again as one of five Muscle Cars stamps.  (General Motors Chevelle and Pontiac Trademarks used under license to the USPS.)