CdA list

[Cd]

Originally Posted by Daox

That would be the new xB has the Cd of .32. The older (smaller more boxy) xB is .35. Radiused edges on the front and sides do wonders for aerodynamics.

.35 for the XBox ? Wow !

Almost nothing seems to surprise me anymore with aerodynamics.

Consider that the first generation Focus hatchback, with its' sloped bullet nose, long roof line, and overall clean " look " had a Cd of .36 !!

I would never have guessed that an XBox would out-aero a swoopy looking Focus hatch !

BTW folks, I think it is either Car & Driver or Road & Track that will sometimes print Cd, as well as CdxA figures in their spec sheets when they do road testing. ( I'll try and update this post when I find out )
Strange as it is though, they leave out this information on all but one segment in the magazine. What makes it odd, is that it does not matter the vehicle - for instance they tested some Nissan Armada SUV thingee and had full Cd and Cda figures published, yet they tested a swoopy looking car in the same magazine, but did not have any figures at all.

[alohaspirit]

Originally Posted by Cd

.35 for the XBox ? Wow !

Almost nothing seems to surprise me anymore with aerodynamics.

Consider that the first generation Focus hatchback, with its' sloped bullet nose, long roof line, and overall clean " look " had a Cd of .36 !!

I would never have guessed that an XBox would out-aero a swoopy looking Focus hatch

that does seem weird to me too

I would have thought the xB [>cd] focus hatch

[alohaspirit]

i think this might have been stated but..

Honda
last gen crx .31
last gen crx .30 (mirror delete)
last gen crx .29 (mirror delete, rear wiper, slim tires)

5th gen coupe .32
5th gen hatch .31
6th gen hatch .36


1996 Dodge Caravan Base Minivan
Coefficient of drag: 0.35

1996 CHEVROLET ASTR0 VAN LT ALL-WHEEL DRIVE
Coefficient of drag 0.40

1996 Toyota Previa DX Minivan
Coefficient of drag: 0.33

Pontiac TransSport
CD: 0.30

[lunarhighway]

did a photoshop pixel count to find my frontal area and the value comes pretty close to the W x H x.81 method, although it turns out the data for my car did not included the width of the mirrors, just the body.

so here it goes:

vectra A (hatchback) 1988 - 1995


width-mirrors (carfolio)
1700mm - 66.9inch

width+mirrors (photoshop calculation)
1945mm - 76.57inch

height (carfolio)
1397mm - 55inch

frontal area (photoshop calculation)
1,92 m² - 20,66sq.ft

Cd
0.29 (carfolio .etc)

CdA (calculated)
0,5568 CdA m² - 5,99 CdA sq.ft

[Daox]

I have updated the list with all your additions. Thanks!

[RobertSmalls]

Two other independent lists:
Automobile drag coefficient - Wikipedia, the free encyclopedia
Automotive aerodynamics - Wikipedia, the free encyclopedia

What I really want to see is CdA data on modified cars. So, in .csv format:

Make,Model,Year,Cd,Height (In),Width (In),Frontal Area (ft^2),CdA
Aptera,2e,prototype,0.15,,,19.9,2.98
Volkswagen,1L Concept,,0.15,39.6,49.2,11.0,1.63
Aerocivic,Civic Hatch,1992,0.17,50.9,66.9,19.9,3.38
GM,EV1,1996,,,,,3.95
Subaru,Legacy Wagon,1995 - 1998,0.32,57.1,67.5,22.5,7.19

Aerocivic data from aerocivic.com. I'm sure the coastdown testing generated CdA data, which was then divided by a guesstimated value of A. I then multiplied the reported Cd by my own guess of A. I would love to know if this matches the CdA from the coastdown testing.

If so, then the conclusion is powerful: Most compact cars have very similar CdA, and I would only gain a 14% improvement in aerodynamics by trading my Subaru wagon in for a Civic hatch. Even the Insight is only 30% better than my car, but the Aerocivic moves through the air with 49% the effort of the Subaru.

If you want a slick car, you have to build it yourself?

If anyone has measured the CdA of their cars before and after aeromods, I'd love to see your results.

[Allch Chcar]

Aeromodding is like hotrodding, if you want it done better you got to do it yourself. Going from a Subbie to a 2 wheel drive vehicle will get you at least 10% just from reducing driveline losses.

The Subbie could be a fun aeromod project, I considered it along with other vehicle bases. But the complications of dealing with transaxle also applies to 4 wheel drive vehicles and that eliminated it from my considerations. It's not impossible, but it wasn't what I was looking for in a vehicle. If you want to try something radical with your Subbie we'd love it if you shared the project with us . I've seen a RWD conversion on a Subbie, it wasn't worth the few hours it took to make the front driveline vestigial. If you keep the car keep the 4 wheel drive, it's worth it .

BTW, when comparing how much power it takes to move a car; 1% is an improvement, 3% is worth some risk, 5% is a good investment, at 10% you're a fool if you don't do it. 30% is huge even if the biggest difference is the small frontal area. Do what you can with what you got, it'll go farther.

[wwkayaker]

2005 Mitsubishi Lancer ES
cd: 0.30 (found at Buy Cars Online, New & Used Car Search, Auto Classifieds)
Frontal area: 25.10 sq ft (54.1/12*66.8/12*0.81)
CdA: 7.53 sq ft

[Daox]

The list has been updated again. Thanks for the additional info.

[Southcross]

I like my car's numbers:

Volkswagen Rabbit 1975-1984 (cD will likely vary depending on year/submodel, i.e. GTI has front air dam and wheel well lining, others don't)
cD: .36 (body frontal area identical to 1st Gen Scirocco (pre-81))
Area: 19.08 sq ft
cDA: 6.87

Numbers for 1st gen Scirocco:
'80 Scirocco
cD: 0.360
Area: 19.08 sq ft
Source:
Mayfield Company
The Mayfield Company Homepage - Volkswagen Vehicle Drag Data