Use a magazine or (better) sheet of still board held at angle in air stream as an air deflector - 45 degrees or so from forward facing with leading edge into wind while driving works wonders (This may or may not violate Oz regulations :-) ).
In the days of "quarterlights" the same effect was achieved by rotating them about 135 degrees from closed so the blunt front edges protruded into the air flow.
And it makes YOU cool immediately while the car interior follows. |
Small solar powered window fans do not have enough airflow in hot sun - even in NZ. Ask me how I know. Something I haven't tried but intend to is to enable either the airconditioning fan or a suitably larger in-window unit to get useful air changes. Battery life needs watching.
Leaving all windows somewhat down works quite well. This adds a security hazard. I've seen lock-in grills that provide substantial open spze and which slot over window glass and into top of frame. Wind down - insert-wind up to lock in place. Probably very effective.
Tasteful foil covered whole of windscreen fold out sheets have their place. try this: Stand somewhere say 1 floor up as close to vertically above car as possible. Look down onto car. Be amazed what % of total projected looking-up area is in glass. I'd guess at over 50% in the car you show above. Effectively reducing that area with window screens is going is going to help.