6% Improvement from... 3 aero wheel covers?
 

So I did something very strange today...

Ordered a set of 4 15 inch aluminum pizza pan covers, some zip tie anchors, and some zip ties from Amazon.com last week. Got them in a few days ago, but didn't do anything with them until today.

Spent this afternoon figuring out how to attach them to my rims. It was a bit of a challenge on the rear, since the brake drum backing plate pretty much covers the entire area of the wheel. There's like a 1/2 inch gap between the backing plate and the hardware.

Finally ended up using the anchors in a star pattern on the pans, drilling a hole to one side of each of them, and zip-tying the pans to the wheels in a star pattern. I did both rear wheels, but only the left front wheel. I ran out of time, for one; and I wanted to make sure that the front brake hardware would not chop up the zip-ties to the point where the left front pan would fly off and become a pizza pan of death.

Drove into work with 3 of the pans installed, and figured that if I would have optimistically improved my C(d) by 5%, then I would see a corresponding reduction in fuel consumption from 2.78 to around 2.6 (figuring this out in my head as I was driving).

Well, I did not get 2.60 gallons consumed.

I got 2.62, instead. That works out to 22.5 MPG, or a 6 percent increase from what I got yesterday. That's pretty impressive, and I am looking forward to seeing what sort of improvement I'll get from installing that 4th pizza pan.

Cool improvement!

It sounds reasonable depending on how bad the rims were for aero.

t vago -

6% better implies 21.2 MPG the day before. Pending long-term verification, that's a 1+ MPG improvement. Below it says that you should be seeing a 0.01 Cd gain :

http://ecomodder.com/forum/member-cf...3-option10.jpg

I think 0.01 Cd improvement usually results in a 1 MPG gain on average, so I think your results are in line with what you should expect.

CarloSW2

It just seems so high, though. I would have expected somewhere around 2% improvement. Then again, these are some aerodynamically ugly wheels I'm correcting. Wheels really affect FE that much?

http://www.finishlinewheels.com/prodimg/ALY02082U.jpg

Eh... I'll do a comparison tonight when I drive back. The commute to work is a net 300 foot decrease in elevation, which makes my to-work FE higher than my to-home FE.

t vago -

It's a fair question. Getting 1+ MPG even fits the downhill commute, so I am hoping for sub 1.0 on the way back. When aerohead reads this he will have the real stuff.

CarloSW2

Well On the areo trix the smooth wheel covers got me 1.5 MPG from a base of 33 MPG

I consumed 2.76 gallons getting home.

So...

Before:
W: 59.0 miles / 2.76 gallons = 21.4 MPG
H: 59.2 miles / 2.85 gallons = 20.8 MPG
T: 118.2 miles / 5.61 gallons = 21.1 MPG

Now:
W: 59.0 miles / 2.62 gallons = 22.5 MPG (+5.3%)
H: 59.2 miles / 2.76 gallons = 21.4 MPG (+3.3%)
T: 118.2 miles / 5.38 gallons = 22.0 MPG (+4.3%)

Okay, maybe not a 6% increase, but still...

If that is the case it would not matter how many he has on, one would give the same result as 3 or 4.

@Old Tele Man: I don't think so. My commute consists of about 3% in-town driving, and the highways are pretty much dead at 1 am. This enables me to set the cruise to 7 MPH over the highway speed limit, so I can focus on scanning ahead for deer and Toyota trucks going at 20 MPG without their lights on (yes, I actually saw that last night), without trying to consciously keep a steady speed.

Now I go out and install the final aero wheel cover. FE should go up slightly, I think.