[Christ]

The design just seems intentional, like the engineers knew that they could alter the wake's profile by putting the exhaust there... maybe I'm reading too far into a purely aesthetic feature?

EDIT:

The best thing I can find is that placing the exhaust in the wake of the vehicle actually increases torque across the RPM range, due to added scavenging... that, in combination with exhaust length/size tuning, could yield a very admirable result, but short of having a turbine engine, or a very small wake area in the rear of the vehicle, after some good 'ole google research, I don't think the average car could really benefit in aero from placing the exhaust in the wake.

Turbocharged cars could benefit from quicker spools, due to the lower pressure differential, N/A cars and supercharged cars could benefit from increased cylinder exhaust pulse manipulation (scavenging), but no aero benefit has been evidenced that I could find.

Still, that Zonda has a 7.3 liter V12... you know from science that if at any point, it is working with 100% VE, it is consuming and exhausting 7.3 liters per revolution..

Speculation from here on:
IF that engine works with 100% VE at (speculatively) 2000 RPM, it is then using/exhausting a total of 7.3L*2000=14,600L of air per minute. (Damn, that's alot of air!) For a total of 515.6 CFM exiting the tailpipe of that car.

Compared to the obvious wake area of the car, it seems like this might make a bit of difference in the wake's profile at speed, and possibly during acceleration.

That's the furthest I can get, I don't know how to calculate airflow at speed, and I dont know the wake area of the car, nor what speed it would be going during this exhaust profile.

Hopefully someone else can take over from here?

EDIT again:
Is it possible that manipulating the shape of exhaust flow could further alter the wake's profile?