I am building a custom car with the following rear end shape:
When I showed this on one forum, a member claimed there was no way air could flow around the taper and said my design couldn't possibly hit under 0.30 CD regardless of the otherwise gently sloping shape (the hood slope joins all the way down to the floor, no bumper deadzone, no discontinuities between the hood/windshield/roof/tail).
Is the taper actually hurting my design vs. say, an untapered fast back shape or even a curved hatchback design like on a Chevrolet Sonic?
I know it's no boat tail, but I wonder how tapering could be, perhaps, worse than nothing.
Assuming I failed miserably at designing the rear shape, any crafty ways/places from which to duct air to fill any discontinuity vacuum in the rear?
I('d) really appreciate any help here.