Drag vs speed curves available for modern cars 2

[2dye4]

Due to this gas thing i would like very much to see a curve of the total rolling resistance vs speed for my two cars. Rav4 and Sienna.

I originally set out to measure these myself by finding a lone flat stretch of highway on a windless day and run er up to 75 mph and record the coast down. Fit this to a curve and differentiate and get a rolling resistance proportionality.

I searched Google but had no luck locating this type of data. I don't want the values calculated using ideal formulas and drag coefficients, as the real thing is bound to be better. Does anyone know of a site with data like this.??

Thanks

 

[J42]

EPA publishes a considerable amount of vehicle data for each model year at the following URL:

http://www.epa.gov/otaq/crttst.htm

Included in the downloadable data files are target A, B and C coefficients generated by the auto companies from coast-down data that are used for setting up chassis dynamometer road-load. You will be looking for the "target coefficients", not the setpoints.

Road force can then be calculated from the following:

F_r = A + Bv + Cv^2

where the coefficients have units of lbf, lbf/mph and lbf/mph^2, respectively, and v is velocity in mph.

Also note that you can look up the manufacturers emissions test results over different drive cycles within the same data set. It's all public information.

 

[EdDanzer]

J42

How is the best way to read the text file downloaded from the EPA web site? The text files look like they should be in a spread sheet so you can tell what header the number matches.

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com

 

[70AARCUDA]

...first, download the *.TXT file, then use EXCEL "conversion" to "reassemble" the columns properly

...it's probably a CSV-file (Comma-Separated-Variables).

 

[crysta1c1ear]

http://www.epa.gov/otaq/cert/veh-cert/cert-tst/08actrr.zip

I downloaded one of the files, saved it with a .CSV file extension instead of .TXT (after looking at it with an editor), and just clicked on the file to start my spreadsheet program and load it.

The field seperator was actually TAB rather than COMMA.

 

[murpia]

Note that you can just drag the .txt files into an open Excel and they work correctly.

Can anyone explain to me the two sets of road load coefficients labeled 'Target' and 'Set'? What units are they in and which should I use in a simulation?

The links on the EPA site to the actual test procedures are broken or empty, although I can find the drive cycle data OK. Can someone please point me to a download (or purchase) of the test procedures?

Regards, Ian

 

[EdDanzer]

Aymeric Rousseau of Argonne provided this statement “Right now there is no good database for real world drive cycles in the public, or maybe even in the private. We need more publicly available information.”

http://www.greencarcongress.com/2008/09/argonne-study-h.html

and

http://www.nrel.gov/docs/fy08osti/42469.pdf

Ed Danzer

http://www.danzcoinc.com

http://www.dehyds.com