well it also depends on gearing and getting your power at the right RPM to be at that speed. Also I am thinking that that would take every bit of power to get to the indicated speed so it may take a while to get up to the top limit aero speed.
It seems that weight does not have that much effect on the top speed with that calculator. the frontal area and CD do which makes sense.
I will be doing some type of elongated nose on my Z but not a Gnose. ere is sort of what I am thinking of for a good front end design. I am going to change it so that there is a piece in front of the hood like on the Gnose but a little different. Maybe like the front of the
... I am thinking that keeping the sides of the car flat(unlike the subtleZ, scarab, and others) is important to keep airflow smooth along the body. This sketch has the sides of the car pushed out about 2" along with a widened BRE-type spoiler.
Before HybridZ goes to the wind tunnel someone should do some road testing to see what obvious things are hurting aero and what things are good. That way we know what to look for in the precious tunnel time. Obviously flow seperation at the hatch and what happens at the windshield are things to look for but also things like what happens in the wheel wells and along the side of the Z's body would be interesting to see. I would be out there today with my yarn and a chase car videotaping if I had my engine back together(may be happening this week)...
HOTROD magazine did some aero testing on a hotrod in a wind tunnel a while back so that may be something to look at.
Just tossing around some ideas here so that is my 2cents...