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Old 09-14-2016, 10:34 PM   #41 (permalink)
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Quote:
Originally Posted by ChewChewTrain View Post
Ah. Thanks. So the benefits of a slippery car don't shine until you do freeway speeds.

According to the Cummins' MPG research, speeds below 55mph is mostly a rolling resistance game. Speed above 55mph turns into an aerodynamic game.

For those that might have missed my posting, you can read it here:
cumminsengines.com/uploads/docs/Secrets%20of%20Better%20Fuel%20Economy_whitepaper. pdf
Also: "Did you know, for example, that a Model S (with a 0.24 Cd and 6.2 sq ft of drag area) requires just 14 horsepower to maintain 70 mph, 4 hp less than a Leaf (with a 0.32 Cd and 7.8 sq ft drag area) ?".

greencarreports.com/news/1092373_aerodynamic-tesla-model-s-electric-car-wins-the-wind-tunnel-wars

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Old 09-15-2016, 03:01 AM   #42 (permalink)
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New Audi A4 has a Cd of .23

A Drag Coefficient of .32 seems a bit high to me as well, especially when considering that the new Audi A4 has a Cd of .23.
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Old 09-15-2016, 04:39 AM   #43 (permalink)
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Quote:
Originally Posted by ChewChewTrain View Post
Ah. Thanks. So the benefits of a slippery car don't shine until you do freeway speeds.

According to the Cummins' MPG research, speeds below 55mph is mostly a rolling resistance game. Speed above 55mph turns into an aerodynamic game.
no, i disagree. in the city ok, but over 50 km/h the aero kicks in. at 80 KM/h the 0,32 car has to face a 15% higher drive resistance than the 0,26. and keep in mind, the prius 4 has 0,24 now.

i heard a rumor, the germans messure the cd without mirrors, with the smallest engine (and radiator), with taped gaps and so on. japs and americans matching the real world mutch better...
if the volt has real world 0.32 so its disappointing anyway, due to the prius numbers. IMHO
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Old 09-15-2016, 08:34 AM   #44 (permalink)
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i heard a rumor, the germans messure the cd without mirrors, with the smallest engine (and radiator), with taped gaps and so on. japs and americans matching the real world mutch better...
if the volt has real world 0.32 so its disappointing anyway, due to the prius numbers. IMHO
That would be interesting to know if that was true since each of these manufacturers are coming out with the CD themselves. Any links to where you read that by chance?
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Old 09-15-2016, 09:49 AM   #45 (permalink)
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Aero is pretty important at nearly any speed cars travel these days, that includes city driving in my opnion. If you look at our Aerodynamic and Rolling Resistance Calculator, the default numbers are for a mid 90s Geo Metro. Below is the chart. As you can see, even at 30 mph, more than 50% of the power required to move the car down the road is already going towards pushing air out of the way.

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Old 09-15-2016, 10:52 AM   #46 (permalink)
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Quote:
Originally Posted by kurzer View Post
japs and americans matching the real world mutch better...
Nissan leaf Cd numbers:
Official:
mk1 0.29
mk2 0.28

INL mk1: 0.342 (Idaho National Lab)
My measurements, mk2: 0.334 (Forum)
Car&Driver mk2 0.32

Last edited by paconassa; 09-15-2016 at 11:38 AM.. Reason: incomplete...
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Old 09-15-2016, 11:31 AM   #47 (permalink)
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Prius 3 is 0,25 vs. 0,26
and the MB CLA is 0,23 vs. 0,3

messured in this test: Drag Queens: Aerodynamics Compared – Comparison Test – Car and Driver
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Old 09-15-2016, 11:46 AM   #48 (permalink)
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Quote:
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MB CLA is 0,23 vs. 0,3
"Mercedes does not fit special features such as automatic grille shutters to U.S. models"

Important difference
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Old 09-15-2016, 01:10 PM   #49 (permalink)
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The Tesla Model S and the gen 3 Prius are a virtual TIE for CdA.

Think about that. Cd is more important than frontal area.
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Old 09-15-2016, 01:13 PM   #50 (permalink)
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Quote:
Originally Posted by kurzer View Post
Prius 3 is 0,25 vs. 0,26
and the MB CLA is 0,23 vs. 0,3

messured in this test: Drag Queens: Aerodynamics Compared – Comparison Test – Car and Driver
It seems they measured 0.30 for the Gen1 Insight in that same wind tunnel.

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