Rear spoilers and safety?

http://www.vtec.net/articles/view-article?article_id=117652 We're done
here!

Rgds, George Macdonald

"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??

 

http://autozine.kyul.net/technical_school/aero/tech_aero.htm

"The wing has the effect of directing the majority of air flow to
leave the roof straightly without going to the back, this reduce lift.
(If we increase the wing angle, a hundred kilograms of downforce may
even be available.) There is still a little bit air flow follows the
back and leave the tail under the wing. This avoid turbulence that
appears in non-fastback car, thus remain drag-efficient. Since there
is too little air follows this route, its contribution to the lift can
be easily cancelled by the wing.
Wing must be installed high in order to be benefited from the
majority air flow. Escort RS Cosworth is right (see pictures) Cougar,
well, seems to use wing as decoration only.

http://www.epinions.com/content_3625296004