I actually saw a video of a guy who drives a car in reverse. As in, backwards going forward. I think it was in Britain. Anyways, it was the most unnatural looking thing I have ever seen. Quite a funny video... if only I could remember the details.
Could we conclude that the designers couldn't keep flow attached past the point where they cut it off, or just cut it off at that point because having a boattail would look too weird?
I forget the term for the lopped-off aerodynamic shape you see on the Insight and CRX (among others), but my understanding is that as you extend the taper, you get less and less efficiency return per unit length of extension. The airflow stays attached, but the additional surface area of the taper has it's own frictional losses. There comes a point where it makes more sense efficiency-wise to end the taper and use an aero fixture such as a spoiler to create a relatively clean detachment point
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.