Tried a few models of having 1 or 2 naca duct or have the top surface slope down as much as possible. However any of these don't reduce the drag much as they disturb the air earlier, causing more turbulence. The only solution that might help is the last one, which slopes down as much as possible without interfering me getting out of the car in emergencies. This reduces the low pressure in the cockpit opening.
I like the second design better than the first as it will most likely be easier to manufacture especially for the mounting for the rear wheels compared to the first one. But I have concerns about the airflow under the car as it might churn up and cause large amount of drag or it might keep its laminar flow??
I don't use NURBS surface modeling for my models, I use Solidworks CAD software to make all of the bodies including the chassis component and so on. I could export the body shape into another software for flattening but to be honest the body is all compound curves to keep the airflow attached. The second body design will consist of two parts, plus a nose cone and am planning to make simple moulds for it.