29. 1969 Chevrolet Corvette ZL-1
In the late ’60s, Chevrolet helped racing teams through its “backdoor” programs where they developed special engines and components. In the late ’60s, the Can-Am was a popular racing series featuring prototype class cars with V8 engines. But Chevrolet wanted to purpose-build a power plant for this championship. So in 1969, they produced an all-aluminum 427 big block called the ZL-1. It was a high-revving, 7.0-liter V8 delivering up to 550 HP in mild. This monster of an engine was far more powerful than anything Mopar or Ford had in production at that time. Chevrolet produced approximately 200 of those engines. While most of them went to their Can-Am racing teams, Chevrolet also built around 12 test Corvettes with the big-block engine in late 1968.
Although the performance potential was unbelievable, Chevrolet didn’t want to offer this racing engine to the public. So they never mentioned the ZL-1 option in the press or their official brochures. However, wealthy drivers close to the factory knew about its existence and could purchase the ZL-1. That is why only two Corvette ZL-1s are known to exist, a yellow and a white one. But Chevrolet destroyed the rest because they were just pre-production prototypes. Only two went to private owners, where they have preserved them as the most valuable, interesting pieces of Corvette history. The ZL-1 model cost $4,000 over the base price of the big block Corvette C3, which was a price few people could pay. And today, the estimated value is over $1 million.