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Old 09-03-2017, 08:56 PM   #1 (permalink)
EcoCivic
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How much do grill openings effect Cd?

I have heard that between 1/4 and 1/3 of the aerodynamic drag on a car is from the cooling openings. That sounds like a LOT of the drag on a car is from air going through the radiator, and I have a hard time believing that cooling causes 1/4 to 1/3 of the aerodynamic drag on a car. If that were the case, wouldn't I have lost a measurable amount of gas mileage when the front grill fell off my 2005 Civic? I was sure that having a big hole in the front of my car would hurt highway mileage at least a little, but the effect on gas mileage even at 60-70 MPH on the highway was not measurable. Also, if drag from cooling was so significant, why do people only get 1-3 percent MPG improvements, presumably mostly from faster warm up, from a full grill block? nPlease help me understand!

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