I think part of the front end design was shaped by laws requiring a human safe zone in the front of the car. My understanding is that every car on the road must not push a human under the car but up and over the hood. Maybe that's why the front end has that indent.

The optimum subsonic shape is a hemisperhical nose with a long tail tapering to a point ( like an ice-cream cornette on its side, with the dome of ice-cream heading into the wind ).

The K-tail is an abbreviation of that impractical-for-cars long tail which gives most of the effect for much less effort.

The Tatra T77 was an attempt to implement the optimum form though even then the tail was somewhat abbreviated:

http://tatra77.com/