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Old 04-13-2009, 03:58 PM   #20 (permalink)
Ernie Rogers
Ernie Rogers
 
Join Date: Feb 2008
Location: Pleasant Grove, Utah
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I get fuel economy from a simple model.

Quote:
Originally Posted by Frank Lee View Post
"..Cutting Crr in half causes—
...at 60 mph: 14% better mileage
...at 40 mph: 20% better mileage."
Is that true?
Hello, Frank,

That breath-takingly long post-- at the very end, I gave the formula for calculating fuel economy. I set that up for myself in an Excel spreadsheet, and I use it to evaluate car ideas. You can also find this calculating model posted in various places on the internet, but I can't tell you where to look.

The point is, these numbers come out of the car fuel economy model. I have checked the model many times and found it to be reliable. Now, about reducing Crr--it's especially interesting to me that sometimes you CAN cut the rolling resistance in half. Tire Crr varies tremendously with brands, sizes, and tire pressures.

So, yes, it's really true. Smart tire choices make a BIG difference.

Ernie Rogers
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