[aerohead]

Hucho's book addresses windshield angles and diminishing returns.Also,light defraction limits the angle that a windshield can be laid back,as at some point,all you get is reflected interior images and inability to see out.I favor convex windshields,as they divide the airstream for the roof equally,allow for homogenous velocities over top and sides,erasing C-pillar vortices.Expensive to build,however low drag impossible to achieve without.