I recently bought a high mileage 06 6MT coupe to drive to work. Love it. Loads of fun. May take it to a track day event soon.

Looking over the specs I like the additional sporty stuff that comes on the 6MT like the front bumper, sills, forged 19's, rev up engine and all that. But, I'm not sure what the rear diffusers are or do. The spec sheet says this:


Aero Package: rear spoiler and rear
underside air diffusers (located on both sides,
rear of fuel tank) – produces zero lift and
0.28 Cd

So what are these? What do they look like? Are they under the car or is it just part of the trim below the bumper? Do they seriously do anything or is it hype? And what is Cd?

Sorry to be so ignorant, but thanks for any help.

George

 

Here's a pic (totally stock) of my last off road trip:

 

i cant find a pic and its too dark for me to get a good picture... all they are is plastic things right in front of the rear wheels. i really do not see the point in them

 

The diffusers are basically plastic pieces that cover up and fill in voids where there would normally be an opening in the bottom of the car. The whole point is to make it so air rushing under the car at high speeds doesn't catch in those empty spots and create lift.

We really don't need them in our cars.... they aren't race cars, and they're not that fast.. I highly doubt many of us are going to be taking corners at 110 MPH or any other situations where such small amounts of lift are going to create a noticeable handling problem. That being said... it's cheap enough for the manufacturer to add them, that I guess it's nice to have them there in the event that they are needed, plus it gives them something else to brag about in the spec sheet and sales brochure.

 

Thanks guys. Sounded like hype to me too. Wonder what the figure they gave means? Coefficient of drag? If so, sounds like the diffuser adds drag....which lowers speed and decreases gas mileage? But, if its benefits are unmeasurably small I guess its effect on overall drag is too.

Will I be taking corners at 110? I doubt it, but maybe turn 10 at Carolina Motorsports Park one of these days. I wouldn't pay extra for the 'diffuser' but I'll take all the help I can get.