Chevy Bolt's aero is a 'disaster,'

[Fat Charlie]

From autoblog:

Design team leader Stuart Norris called it a "disaster for aero." They made it "big and spacious," getting a Cd of 0.32. The standard tricks of aluminum, a spoiler, underbody panels and an active grille are meant "to compensate" for it.

They killed the aero to get interior utility. On a platform who's selling point is efficiency. I'm not a fan.

[Daox]

I wouldn't call .32 a disaster, but it certainly is sorely lacking compared to most vehicles these days which are sub .3 if they're trying at all. It would be very interesting to see the difference in range between .32 and lower CDs.

[Fat Charlie]

It wasn't me, the lead designer called it that. He doesn't sound happy about being told to add more cubic feet. They even had to say that normal tweaks weren't to "make it even better," but to "make it less bad."

[mcrews]

it's the 'design' team leader. of course he's upset. design and reality and sales are very different things.

[oil pan 4]

What's the frontal square footage?
Cd is only half the equation.

[samwichse]

Originally Posted by Daox

I wouldn't call .32 a disaster, but it certainly is sorely lacking compared to most vehicles these days which are sub .3 if they're trying at all. It would be very interesting to see the difference in range between .32 and lower CDs.

It's no better than the 2017 Honda Fit, which is much more concerned with keeping the body short and easy to park than aero. That will certainly hurt the practical highway (70-75 mph for the average joe) range considerably, no matter what the EPA highway test cycle range says.

Disappointing.

[kach22i]

Originally Posted by Daox

I wouldn't call .32 a disaster, but it certainly is sorely lacking compared to most vehicles these days which are sub .3 if they're trying at all. It would be very interesting to see the difference in range between .32 and lower CDs.

Could you provide a link?

Very few cars on the road have that low of a Cd in my opinion.

The Cd of .32 is respectable, the current Porsche 911 has this Cd, it is one of the lower ones, not Prius low, but at least sports car low.

I did find this link, older model cars though.

http://www.mayfco.com/dragcd~1.htm

[samwichse]

0.31 Honda Civic (Sedan) 2006-2011
0.28 Honda Civic (Coupe) 2006-2011
0.27 Honda Civic (Hybrid) 2006-2011

Wikipedia:
0.28 Hyundai Elantra 2011
0.28 Chevrolet Cruze sedan [99] 2015
0.29 Chevrolet Corvette 2005

Here's the one that gets me, two electric hatchbacks, both significantly (~10%) better aero than the Bolt:
0.29 BMW i3 2013
0.29 Nissan Leaf 2010

0.31 Nissan Versa 2004
0.29 Nissan Versa 2007–2008

0.29 Toyota Yaris 2006-2011
0.28 Chevrolet Volt 2010-2015
0.275 Ford Fusion 2013
0.27 Mazda6 (sedan and hatchback) 2008
0.28 Mazda3 (Hatchback) 2012
0.277 Toyota Auris hatchback 2013
0.27 Volkswagen Golf Mk7 2012–present

Yes, they could have done much better.

[Hersbird]

Originally Posted by Fat Charlie

From autoblog:

Design team leader Stuart Norris called it a "disaster for aero." They made it "big and spacious," getting a Cd of 0.32. The standard tricks of aluminum, a spoiler, underbody panels and an active grille are meant "to compensate" for it.

They killed the aero to get interior utility. On a platform who's selling point is efficiency. I'm not a fan.

I don't get why he's blaming the size for the bad Cd. Isn't a larger car actually easier to get a lower Cd? Granted the overall drag is higher but basically this engineer is complaining they had bad aero along with a larger size, a double penalty. I think I read the 2017 Chrysler minivan is .30 Cd. Bad aero isn't because of the size, it's because of bad engineering.

[kach22i]

Originally Posted by samwichse

Yes, they could have done much better.

Thank you for the list, but could you please cite your source of information?

I think it's been at least 3 years since I looked at a complete Cd list, certainly improvements have been made fleet wise I can see.

Such a jump may be connected to EPA fuel economy regulations. I wonder if there is a chart for this.

Found this.......(see below)........several charts and graphs in link below.


Corporate Average Fuel Economy
https://en.wikipedia.org/wiki/Corpor...ation_proposal

Model year 2012-2016 Obama Administration proposal

The new policy will result in yearly 5% increases in efficiency from 2012 through 2016...........

A 4 or 5 mpg improvement from 2012-2016 (looking at "Agreed standards by model year, 2011-2025" chart in link), I'm guessing much of this because of aerodynamic design effort and study. However I have no support for this belief other than the numbers samwichse posted and my memory of what Cd's used to be a few years ago.