2.5 LITER PERFORMANCE MODS

If you follow the styling backwards, to the Nash Ramblers, there's a styling continuity. The placement is a style choice that has passed. Here's 1960, if you think 61 to 63 is forward!

wittsend has it correct -- the wheel forward in the wheel well gives the illusion of the car in motion even though it's sitting still -- and perhaps that it's going faster than it seems. I forget where I read that, but IIRC it was a comment made by Ed Anderson, the head of AMC design at the time. It was just styling, and as TomJ mentioned, it's a styling "fad" that has passed...  I kind of like it because it's Rambler unique, makes the car look more like a Rambler and not everything else.

Aerodynamics. Nash did wind tunnel testing when designing their new cars released in 1949. From https://www.allpar.com/threads/nash-motors-cars-1916-to-1954.228277/: "The aerodynamic 1949 Nash "Airflyte" was the first car of an advanced design introduced by the company after the war. Its aerodynamic body shape was developed in a wind tunnel. Nils Wahlberg's use of Breer, Zeder, and Skelton's theories on reducing an automobile body's drag coefficient resulted in a smooth shape and enclosed front fenders; both 600 and Ambassador models, on a 112 and 121 inch wheelbase respectively, had the same body."