The journey for Porsche to LeMans glory starting in 1970 is almost a textbook case of incremental evolution. A new trait here works, so it sticks. A few things lost in the name of ultimate high-speed glory.
Seeing the 1966 Porsche 906 Carrera 6 beside a close descendent, the 1968 908K, makes clear how carefully Porsche was refining its alloy spaceframe racecar during the 1960s. They really knew they were on to something with the ultra-low boxer engine masses, mounted right behind the driver for optimal handling. The 2.0-liter six of this racecar shares much of its fundamental design with the 911, and would ultimately enhance the 911 range with its extra power.