Porsche built its reputation on small, lightweight cars with tiny flat-four engines that beat the best the world had to offer. But technology didn't stand still, and the last of the four-cylinder "giant killers" was the 904 GTS. Delivered new to California, this 1964 904 was raced throughout 1965 before being sold on to its most famous owner — actor Robert Redford. Redford kept the car for nearly a decade before selling it on, where it eventually ended up in Belgium. Restored in the early '90s, the car has its original transaxle, while the motor was swapped for a period-correct engine from an early 2-liter 911, the motor the last of the 904s left the factory with. Only 110 904s were made to satisfy FIA homologation requirements, making the car one of the most sought-after Porsche models.