The ideal thermodynamic cycle was discovered in the 19th century [1]. We've known ever since why 200k MPG is impossible and we later discovered the design that

The ideal thermodynamic cycle was discovered in the 19th century [1]. We've known ever since why 200k MPG is impossible and we later discovered the design that evolved into the modern internal combustion engine, a process which was mostly engineering, metallurgy, and the development of industrial quality control. [1] https://en.wikipedia.org/wiki/Carnot_cycle https://en.wikipedia.org/wiki/Carnot_cycle