[Bellerophon]

Aero Dynes were designed for the rear window to be left open when
travelling in order that a through flow of air through the car be established, and
would allow the heating to work properly.
Tony Crook was always insistent that the rear window be left open as anyone
who rode with him would know.
One word of warning regarding the exhaust protruding beyond the rear bumper
on the V8's. It can be very costly if you reverse into anything as it is
very easy to break one of the exhaust manifolds, which are not easy to
replace.
My regards,
Bellerophon