The rear window louvers that were original equipment on some 60s and 70s muscle cars were first and foremost, styling statements. They were part of an appearance package that was created to set these cars apart from lower performance plain Jane versions and were usually combined with features like stripes, spoilers and vinyl roofs. In addition, while they did not improve the aerodynamics of the vehicle, they created a dead air zone that helped traction by reducing rear lift.
Some pony cars, like the 1969 Mustang Boss 302, had fastback roof lines with large rear windows so severely angled they were nearly horizontal. Although the rear window louvers were primarily styling features, they were designed to a specific length and angle to block the maximum amount of sunlight, while minimally restricting the driver's view. Because that great expanse of glass was covered by the louvers, the interior was not exposed, preventing the sun from raising the cabin temperature and fading and drying out upholstery and carpeting, and personal possessions and cargo were not visible to prying eyes and potential thieves.
1969 Mustang Boss 302
Dodge and Plymouth offered rear window louvers, as an option package (Code A44), for the 1970-71 Plymouth ‘Cuda and Dodge Challenger, that included a black vinyl roof. These hinged louvers (also known as backlight louvers) were constructed out of high quality aluminum and were installed with flip-up hinges and chrome hood pins, for ease of window cleaning.
1971 Plymouth Barracuda Sales Brochure
1972 Challenger R/T
For owners of modern Challengers who desire the “old school” look, there are several suppliers of rear window louvers. However, prices, composition and quality vary greatly, from cheap China-made $170 ABS versions that install with 3M tape, to $800 bolt-on aluminum versions, complete with hood pins, that replicate the 70s louvers.
Below, is photo of a 2009 Challenger with well-designed, classic hinged aluminum rear window louvers, and a 1971-style go-wing spoiler.