Car: Buick Skylark Gran Sport
What makes it special: The Gran Sport option was given to Buick's intermediate Skylark model in 1965. Buick sold more than 15,000 Skylarks with the Gran Sport option that first year, and almost as many the next. It was renamed the GS 400 for 1967.
What made it famous: The Gran Sport optioned Skylark had the largest engine permitted by GM, a 400 cu in Buick V8. In reality, this engine was 401 cu in, but called a "400" by Buick because that was the maximum engine size limit set by General Motors for the intermediate body cars. It put out 325 hp and 445 lb·ft and was famously known as the "Nailhead" engine for the unusual vertical position of its small-sized valves, which were compared to nails since their head diameter is smaller than other comparable displacement engines of the same time period.
Why I would want one: It's a no-nonsense, good looking coupe, and has the biggest displacement V8 allowed by GM for the time period. That alone is worth plunking down good money for such a reputable car. Plus, it's not as common on the street as the other GM offerings on the road today. Something "different from the norm."
Fun fact: The name Gran Sport replaced the GS moniker with the 1973 Gran Sport, and was again revived in the late eighties on the FWD Skylark model with various added performance options.
( 1965 Buick Skylark GS photo from barrett-jackson.com )