Pizza pan wheel covers tested!
 

http://i1047.photobucket.com/albums/...ps6444edff.jpg

So, I finally had an afternoon free and decided now is as good a time as any to quantify the numbers on smooth wheel covers on a Gen III Prius. It wasn't an ideal day, what with higher wind than I'd like, so I'll probably repeat this in the spring if I can find a calm day to do it.

Location:

1 mile of Champaign County Road 500E between Curtis Road and CR 1200N was used for testing. I chose this section of road for the low traffic and flatness; elevation is 704 feet at the north intersection, 703 feet at the midpoint, and 701 feet at the south intersection with CR1200N. Despite the location, I still had to redo one set of B runs due to tractor interference (it's harvest time).

Conditions:

Overcast, 59 degrees Fahrenheit. Winds ESE at 12mph. I would have preferred less windy conditions, but this is the only time I had to go out and do this. Additionally, as you'll see from the numbers, I believe windspeed increased a little over the course of the test.

Methodology:

5 sets of N-S runs, 3 with covers (A), 2 without (B), run A-B-A-B-A. I warmed up the car for 30 minutes and verified coolant temperature with Scangauge; I don't have an X-gauge for oil temperature so had to assume that half an hour was enough to bring it up to operating temperature. The car was left on between runs with cruise control set at 50mph; covers were removed and stored in the vehicle on B runs.

Results:

A1(N): 62.3mpg
A2(N): 66.9mpg
A3(N): 67.6mpg

Average: 65.6mpg

B1(N): 61.8mpg
B2(N): 67.2mpg

Average: 64.5mpg

Change: 1.1mpg (1.7%)

A1(S): 61.7mpg
A2(S): 62.1mpg
A3(S): 61.0mpg

Average: 61.6mpg

B1(S): 59.4mpg
B2(S): 60.2mpg

Average: 59.8mpg

Change: 1.8mpg (3.0%)

There you have it, an average 2.35% improvement on a car that represents "typical" low-drag optimization in the current auto market. When I do this again in the spring I'll try and find a set of the stock wheelcovers to test against.


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ADMIN EDIT - Related threads from DIY aerodynamic efficiency modifications:


https://ecomodder.com/forum/attachme...1&d=1217740296 Experiment: smooth wheel discs tested on Chevy S10 pickup - 4.6% mpg improvement @ 65 mph

https://ecomodder.com/forum/attachme...1&d=1348612461 DIY coroplast wheel covers

https://ecomodder.com/forum/attachme...1&d=1337652592 Cheap factory smooth wheelcovers help MPG - Chevrolet Suburban

So that's pizza pan vs alloy wheels ?

Correct, full smooth cover and no cover.

How did you attach them? how do you keep from rubbing through the paint on your nice TRD wheels?

Those wheels are too nice to cover up with pizza pans. I got a nice set of wheels too and was considering some lexan disks. :thumbup:

That's a picture of the stock wheels I found online; apparently, a lot of people add the TRD center caps (I forgot to take a picture of mine before putting the covers back on for the last time). The stock wheel covers the pans are attached to snap right onto those wheels.

Those are the stock wheels for the prius minus the wheel covers? :eek:

No, those are not the stock Prius wheels.

Yes, they are--2012 on they're painted black, 2010-2011 silver.

http://i270.photobucket.com/albums/j...s/Prius004.jpg

http://www.ct200hforum.com/forum/att...e-dscf3153.jpg