Replying to Topic 'Sedan- No Rear Spoiler??'
It depends on what you mean by "effective". Will it reduce aerodynamic lift? Probably. Does that matter? Only at speeds you will get ticketed for. Will it produce "downforce"? No. Would you want it to? No.
[rant]
There is a strong misconception among the uninformed modding community (call them ricers if you like) about the function of a spoiler or wing. After watching some IRL or CART racing, they deduce that a big wing is helpful on a fast car. After hearing some vague information about downforce and how a Formula 1 car could drive on the ceiling of a tunnel because of the downforce the car generates (true by the way) they decide they've got to put a huge aluminum wing on the back of their Civic DX. There are two major problems with this:
1. Aerodynamics is a very complex field and any wing design that will be effective requires a lot of mathematical planning, as well as wind tunnel testing.
2. Most cars made today are front wheel drive, and even if the homemade wing magically DID produce downforce, this would not help our poor misinformed boy racer, because the wing would actually reduce the contact patch on the drive wheels, thus slowing him down, not to mention the enormous drag factor of the wing itself, both aerodynamically and in terms of added weight.
[/rant]
It's unlikely that Mazda has done the type of design and testing necessary to actually make the spoiler effective. They certainly haven't mentioned it if they have. In contrast you can see the example of the Infiniti G35, which boasts an impressive .29 CD without its spoiler, and a .28 CD with. This is in addition to a design which has zero front lift. Nissan has bragged about this design and rightfully so. Mazda hasn't said a peep about aerodynamics, only about visual dynamics. Therefore I deduce that Mazda has designed a car that looks fast but isnt' necessarily more aerodynamic than other cars out there.
So if you buy the spoiler, understand it's just there to look cool. But hey I'll probably get one just because it does look cool.