What does a rear diffuser do?
12-11-2012, 05:16 PM
#3
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It's intended to create an area of low pressure at the rear of a vehicle by channeling and expanding air flow, thus causing the air pressure over the vehicle to press downward. Basically making your car an upside down airplane wing of sorts.
Like he said, most of the time the ones on body kits are cosmetic and BS.
warning NSFE 
Like he said, most of the time the ones on body kits are cosmetic and BS.
Spoiler
06-05-2013, 12:28 AM
#5
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They do help with downforce, but they're main function is to reduce drag by diffusing turbulence at the rear of the car caused by high pressure air under the car slamming into low pressure air at the rear of the car. If your car does not have a flat underbody, a rear diffuser will do nothing for you.
06-05-2013, 07:26 AM
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depending on design it can also help prevent your back bumper from becoming a parachute to trap all the wind hitting the rear muffler, or where it used to be, like on the Genesis.
06-05-2013, 08:16 AM
#7
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For a diffuser to work, you need a flat bellypan. This means there's no air getting into the bumper area anyways. In other words... unless your street car costs over $200k, the diffuser on it is purely for aesthetics.
