Is a spoiler or wing any benefit at legal speeds or is it strictly a cosmetic thing unless you reach higher speeds? If it is a benefit at legal speeds how much does it affect MPG?

Spoilers will reduce a little aft turbulence which = greater speed stability and better aerodynamics. Practically speaking it's not much but it's there. Wings are primarily for downforce and negligible at highway speeds. Unless you have as much wing area as a Lotus Exige which I believe generates 100 lbs of downforce at 100 mph. But you also need to know the wing is only part of that equation since that car was designed with several vents redirecting air over the car to create that much force.

Hi calvin,
This isn't a direct answer to your question, *disclaimer* I don't know enough physics to give you an absolute accurate/appropriate response here. I think it needs to be a certain height or exposed to flowing air to effectively be "pushed" creating down force. However, I had come across an article a few years ago about a toyota prius which was able to increase it's fuel efficiency by 5 mpg on freeway travel at speeds over 65 mph i believe it was. This was done by reducing lift under the front end of the car by using cardboard to make a template, then cutting out that shape with abs plastic and attaching it essentially as far back as to the front wheels. In front of the wheels they had also put little deflectors to reduce drag.

I actually have the article in a zip file some where on my computer along with a bunch of other aerodynamics articles relating to cars and racing. If you'd like, i could email it to ya for more reading.

I had wanted to do this with my miata, even if just for increasing my mpg (along with skinnier side mirrors.. at 80 mph this starts to make a difference of frontal area drag (?)) however I got too lazy, i am worried about getting the proper cooling to the front of the car, thus requiring i get a thermal sensor and barometer to measure temperature and air density while driving both with and without the piece. I think by doing so and perhaps some relief cuts in the hood to direct the air pressure in a desirable way (maybe to compensate for the lack of air flow underneath the car, you can obtain it on top?) but again, this would require a good amount of measuring both outside and inside the hood.

But don't just take my word for it, look at plenty of race cars and you'll see flat underbodies with specific cut outs and lots of holes, cuts and wings on top of the car [cool]

-Colin

Spoilers will reduce a little aft turbulence which = greater speed stability and better aerodynamics. Practically speaking it's not much but it's there. Wings are primarily for downforce and negligible at highway speeds. Unless you have as much wing area as a Lotus Exige which I believe generates 100 lbs of downforce at 100 mph. But you also need to know the wing is only part of that equation since that car was designed with several vents redirecting air over the car to create that much force.
Thanks! that's what I thought.

Hi calvin,
This isn't a direct answer to your question, *disclaimer* I don't know enough physics to give you an absolute accurate/appropriate response here. I think it needs to be a certain height or exposed to flowing air to effectively be "pushed" creating down force. However, I had come across an article a few years ago about a toyota prius which was able to increase it's fuel efficiency by 5 mpg on freeway travel at speeds over 65 mph i believe it was. This was done by reducing lift under the front end of the car by using cardboard to make a template, then cutting out that shape with abs plastic and attaching it essentially as far back as to the front wheels. In front of the wheels they had also put little deflectors to reduce drag.

I actually have the article in a zip file some where on my computer along with a bunch of other aerodynamics articles relating to cars and racing. If you'd like, i could email it to ya for more reading.

I had wanted to do this with my miata, even if just for increasing my mpg (along with skinnier side mirrors.. at 80 mph this starts to make a difference of frontal area drag (?)) however I got too lazy, i am worried about getting the proper cooling to the front of the car, thus requiring i get a thermal sensor and barometer to measure temperature and air density while driving both with and without the piece. I think by doing so and perhaps some relief cuts in the hood to direct the air pressure in a desirable way (maybe to compensate for the lack of air flow underneath the car, you can obtain it on top?) but again, this would require a good amount of measuring both outside and inside the hood.

But don't just take my word for it, look at plenty of race cars and you'll see flat underbodies with specific cut outs and lots of holes, cuts and wings on top of the car [cool]

-Colin
Colin-

Thanks, looks like I need to book a wind tunnel, lol. Just looking for a little extra MPG to make it to 40 on the highway, (and if I can look cool that's a plus.)

Oh man 40 should be easy!
I don't have the spoiler and I can get average of 43mpg highway. Just go the speed limit either 55 or 65 and you should be fine. Setting cruise would be best though.

The only thing you'll get out of a spoiler at legal speeds......being called a "ricer" if it's too big. Or it'll be called "looking good" or something similar, if it's a common spoiler seen around here frequently.

Look elsewhere for MPG gains for your Focus. [;)]

Oh man 40 should be easy!
I don't have the spoiler and I can get average of 43mpg highway. Just go the speed limit either 55 or 65 and you should be fine. Setting cruise would be best though.
70 or 75 is more like it...then again my Focus isn't fully broken in yet.

The only thing you'll get out of a spoiler at legal speeds......being called a "ricer" if it's too big. Or it'll be called "looking good" or something similar, if it's a common spoiler seen around here frequently.

Look elsewhere for MPG gains for your Focus. [;)]

Hahahaha, that's so funny, but so true.[:p]

yea the aluminum ones wire to your engine and add 15 hp

yea the aluminum ones wire to your engine and add 15 hp

...at least! [:p]

Yes a wing will be more of a aesthetic piece than actually seeing any difference in performance at legal speeds

Yes a wing will be more of a aesthetic piece than actually seeing any difference in performance at legal speeds
Thanks, that's what I thought all along.

Well once you hit 70 you'll probably get 37mpg or so max.
Still pretty good though

Well once you hit 70 you'll probably get 37mpg or so max.
Still pretty good though
39, but I have a 2009

See 39 too, isn't that good enough? [race]

With the highways around here I get stuff around 33-47mpg depending on the way I drove and traffic conditions. 47 was no ac and 55mph whole way

good job everyone for not flaming, I haven't done any tests or anything, but would think that I probably get more downforce with my roof rack deflector that would get with a wing on the back. Here's the idea...


wind----> /-------(rack deflector)= pushed back and down...more drag and less mpg (about 2 mpg drop after install)