Yup, long tail is good for aero. Taken to the max:
http://www.wired.com/images_blogs/au...-geo-metro.jpg
I gave my drawing a longer tail because the only real disadvantage is that it's harder to park, but the MKIII Spyder is so short that I wouldn't mind a few more inches of tail. Only one time did I park in a spot where the back of my bumper was literally at the red line, and my front bumper was 1 inch from the next car. There was also an overgrown bush that got a lot of nasty stuff on my car that day, will not do that again.