It's a Kamm back. Named for a German engineer.
The concept is that it's the back end shape of a teardrop taper but it works just as well, or better, if you cut off the taper. You can look up Kamm back in wikipedia.
__________________
__________________
Currently getting +/- 50 mpg in fall weather. EPA is 31/39 so not too shabby. WAI, fuel cutoff switch, full belly pan, smooth wheel covers.
Now driving '97 Civic HX; tires ~ 50 psi. '89 Volvo 240 = semi-retired.