28. Chevrolet Impala SS
The legendary SS or Super Sport package has its place in muscle car history as an important model that promoted performance to the public. This was one of the first high-performance automobiles that were relatively affordable and fast. But everything started when Chevrolet decided to transform their 409 truck engine to use in passenger cars. They discovered that the unit was powerful and could outrun all the other cars on the road. Just by making some mild modifications to the engine, it could produce up to 409 HP, which was enough to propel the Impala from a standstill to 60 mph in six seconds flat. At the moment, that was Corvette territory. So, as a mid-year introduction, Chevrolet presented the SS package which featured bucket seats, sports trim, and other details. And better yet, it came with the 348 V8 engine pumping out a whopping 350 HP.
However, the most interesting option was the 409 V8 delivering up to 409 HP if you optioned for the dual-quad intake system. Despite the fact that Chevrolet sold over a million of its full-size models, they only made 456 Impalas SS that year. But, out of those, only 142 Impalas came with the 409 engine. While the exact number of Impala SS 409 Convertibles is unknown, Chevrolet historians speculate they made around 45 of these cool-looking, immensely powerful open-top cruisers. Interestingly, the 409 option was available for all Chevrolet full-size models in 1961. So although it was possible to find this engine in some plain-looking sedans and wagons, those cars have yet to surface. Today, as expected, the 1961 Impala SS 409 is one of the most valuable cars in Chevrolet muscle car history.