Travelling to and from the Dragons run this weekend, I conducted a 440 mile gas mileage experiment.
From Akron Ohio, to just North of Cincinnati, I cruised on Interstate 71 with my Wing in the raised position going South. On my return trip I kept my wing down over the same section of highway.
Variables?
There were little to no crosswinds.
No head or tailwinds.
Going South air temp averaged in the low 50's.
Going North air temp averaged in the upper 60's.
Air Temp at all 4 fill-ups were within 5 to 10 degrees of each other.
Tank was always filled to the very brim to insure accuracy.
Speeds averaged around 72 mph going South.
Speeds averaged about 75 mph heading North.
About a 240' increase in elevation heading North.
I never coasted, and Cruise control was used constantly.
No Drafting.
Sunoco 94 octane going south, wing up.
Shell 93 octane going north, wing down.
Test performed on a "factory stock" engine with no modifications, original spark plugs, air filters, with 40k miles on it at end of test.
The end result.......(drum roll please)
30.784 mpg with the wing in the "down" position.
28.440 mpg with the wing deployed.
I realize this wasn't a "controlled" test, and I've read where several forum members have posted that they attained higher mpg results the faster they drove. I just thought a difference of 2.34 mpg, was significant enough to mention.
I prefer to believe the increase in MPG is due to the wing being down, and the car is moving thru the air with a little less turbulance.
Oh, and on another leg of the trip home, I was running (with traffic) at speeds of 95 mph (where my audible warning beeper went off) and the car still felt very stable and planted. But I think they programed it to sound off at that speed because any faster, and it would "need" to be deployed to actually do some good.
Remember, this was just a test, do not try this at home. Keep out of reach of children. Your results may vary.

 

How do you force it to stay down? I know how to force it to stay up always, but when i've tried holding the down button, it still goes up @ ~60.

 

Did you take into account elevation changes? You might have been traveling generally down hill in one direction and generally up hiil the other.

 

Yep, looks like he considered it.

 

You can just take the fuse out and it will stay down altough the light on the wing toggle flashes. I did this for gas milage and rear visability. I wish I could just get the speed for auto deploy moved up to 80 and then I could use the toggle if I wanted

 

I think you are right. with the wing down is more aerodynamic.

ANyone want to try putting up the Rear Wheel Well Covers? I think that also improve the aerodynamic as well.

 

I simply installed a "Kill" switch so I could cut off the current to the wings motor.
I'm no electrician, but it was a simple matter of pulling the fuse, and running a wire from the fuse box to the "on off" switch.
Eventually I'd like to hook it up to an old fashion floor mounted head light "dimmer" switch.
Once you flip it on, the wing will work just like it normally does. But you can't get it back down until you're below 35 mph. When it comes back down I just hit the switch and it stays down until "I" want it to go back up.

 

No thanks. If I wanted gas mileage, I'd drive a Corolla. It's a sports car for God's sake....

 

now you know you have that amx hood which is slowing you down just a little....ok, I won't go there....LOL

 

I don't keep the wing down for gas mileage, I just think it looks better down position on my car.
A few forum members wondered if it effected the gas mileage any, and I was curious about it too, since it was so easy for me to check it out, I thought I'd give it a try.
For Gas mileage, we drive our Civic, but I sure can't knock 30+ with a high performance car. (OK, all you SRT guys can stop laughing now).

 

That is pretty interesting. The Crossfire's aerodynamics should be ok up to at least 70 mph. I also drove the Crossfire to around 80-85 mph and it felt stable. My old Eclipse felt like it could be blown off the road at 60...

 

Yeah, but it's oh so worth it. IMO.

 

yeah I like the look of the car better with it down and I hated the the loss of rear visability with it up.

 

I kind of assumed that it hurt the fuel efficiency a bit but nice experiment to show the numbers.

Were you not worried about getting pulled over again for driving recklessly with an undeployed wing?

 

Wing up / wing down; Funky hood or no funky hood -

I thought that your test was great - know most of 71 well - also though that you did a good job explaining all the issues. Know you were probly driving to the dragon for pleasure and why not see what the mileage was all about; rather than some high browed died in the wool all issues detailed out the A** experiment.

thanks - I enjoyed it

 

Ha, ha Joebird, I did think about it. But as soon as I was out of Summit County and away from that paticular Sheriffs Dept. jurisdiction, I figured I was in the clear. The biggest thing I worry about is the OHP, and not having a front plate for them to reflect their radar off of.
MAKIII I'm glad you enjoyed it, it was just for fun, and not meant to be the definitive answer to any specific gas mileage questions.
I never expected such a increase though.
I wish I could have restrained myself, and kept the speed going North exactly the same as I did going South. But we left so early in the morning that we were about the only automotive traffic on the road, so all I was doing was passing trucks.
Coming home, there was a lot of passenger car traffic, and if I would have stayed at the lower speed, I would have been a rolling road block everytime I passed somebody.
Probably the best place to conduct such an experiment would be Florida. Running from Jacksonville, down to Miami and back. Nice and flat, I don't think crosswinds would have much effect, and it has a pretty constant temp. Any takers?
Or another possible test, which gets better mileage, coupe or roadster? Or what's the difference in mpg with the top up vs top down? In a coupe, windows down vs windows up. Inquiring minds want to know.

 

It's interesting, and you tried to take into account a number of variables. And you do disclaim saying the test wasn't controlled. Thanks for sharing this here.

But in order for the results to be meaningful, it would need to be controlled.

Scientifically speaking (high-brow, dyed-in-the-wool experiment mentality), the mileage results you got are "in the noise". As you stated, you've got a number of factors that are not tightly controlled that affect mileage:

• route
• brand and type of fuel on each fill-up
• tire pressure
• weight of the car and contents
• time of day
• position in traffic (drafting vs. leading)

I'd love to get a couple extra miles out of a tank (sounds like you got maybe ~30) but the results are inconclusive to me. One could take any one of the variables (either reported or not reported) and claim that as the reason:

• speed
• temp
• altitude (and atmospheric pressure)
• wind
• unrecorded variables (see above)

Yes, you said it wasn't controlled. Not trying to beat you up. Just observing that this is like the import tuners putting a chrome muffler (can I say "Fart Can on here?") on a car and claiming 2-3 HP increase based on casual, uncontrolled "before" and "after" observations.

Remember, the spoiler (it's not a wing) doesn't create additional frontal area when deployed (which would affect aerodynamics numbers); it "spoils" the air flow, disrupting it as it passes over the car. It is supposed to prevent the car from developing excess lift at very high speeds. The general consensus is that it only creates 40 pounds of downforce at speed, above 80MPH. This is enough to achieve the intended effect but is quite modest. Think of it this way: Two or three bowling ***** in the back would be about the same, though more noisy if left loose...Of course if they were "Crossfire" or "AMX" (close to "AMF") bowling ***** we'd have to revisit this...

Again, I am not trying to be mean. I'm an engineer. That's something of a social challenge when stuff like this comes up... I'm just pointing out that nobody should make any conclusions based on the test. I agree, that people should do what makes them happy.

And clearly all that matters is:



Reason for Edit: My own compulsive nature - should have said 40lbs of downforce above 80MPH

 

Well, actually, the wing is designed to provide approximately 356 Newtons (~80lb) of downward force at 80mph.

(Actually, I did a conversion error, 356 Newtons is more like 40lbs.)

Adding 80 lbs of "weight" will definitely have an impact on your fuel mileage to some degree.

The wing is there for a reason, albeit we may not be driving at speeds to make it matter but remember what happened to those early Audi TTs without a rear spoiler?

 

Geez AMX, you didn't take into account the rotation of the earth !!! And you call yourself an engineer !

 

Yes, but only in reference to mufflers.