Lutz: Chevy Volt aero might have been better if we put it in the wind tunnel backwards
One of questions that went unanswered after the debut of the Chevy Volt earlier this year was the drag coefficient. Last night at a dinner with bloggers before the opening of the Los Angeles Auto Show, GM Vice-Chairman Bob Lutz provided a clue. While talking about the Volt he said that the production version would look different from the concept but will be recognizable as a Volt. When they put the concept into the wind tunnel it was a huge disappointment. Lutz said they might have gotten better results if they put it in backwards.
[Source: Bob Lutz]
Reader Comments (Page 1 of 1)
rob 9:54AM (11/14/2007)
"In fact, some American cars probably have a better drag coefficient when driven backward." - Paul MacCready discussing his AeroVironment teams continuous conflicts with GM designers on the shape of the GM Impact electric car. In the end they got it to 0.19 while keeping something of a conventional shape.
Good thing to see that GM learned its lesson with that work! (that was sarcasm)
Reply
Tony Belding 9:55AM (11/14/2007)
This makes me want to cry. GM -- and most other car makers -- for decades have considered aerodynamics an afterthought, if they thought about it at all. (And at the same time saying they couldn't make more efficient cars!)
Their stylists -- who are treated like rock stars in the company -- design something that panders to the current fashion. Then they put it in a wind tunnel, and the aerodynamics engineers suggest changes. Then the stylists kick and scream and raise hell and claim their "vision" would be ruined by any modifications, no matter how small.
It's stupid.
Now you look at how Aptera designed their car. They designed it in a wind tunnel first, then the aero guys turned it over to the stylists and said, "You can change anything as long as you don't increase the drag coefficient."
That's how you design a car for efficiency.
Reply
Domenick 10:07AM (11/14/2007)
They designed the car without consideration of it's drag coefficient? News like this fills my with confidence that the Volt will be a technological success story.
/s
Reply
greg woulf 10:50AM (11/14/2007)
It's got to look good, or it's useless. People will flock to a Plug-in electric when it:
1. Is the same cost or cheaper.
2. Has the performance.
3. Is more convenient.
4. Looks good to them.
If you want an Aptera go get one, I can guarantee they won't be shutting down OPEC any time soon because Aptera is saving us too much oil.
If you want a real sign that GM has changed note that Lutz was right up front about it. That openess is a huge change, and the fact that they are making changes and that he quite obviously understands the issue is a huge change for the better.
You've got to keep the big picture in mind. If 1,000 environmentalists buy the Volt it doesn't change a single thing. If 100,000 regular commuting economically minded people buy the Volt then it's a huge start.
Reply
Throwback 10:58AM (11/14/2007)
Styling a car in the wind tunnel may be best for efficiency but how many people buy a car because it is aerodynamically efficient? Most people do not look at cars as transportation appliances. We want cars that look good, and are willing to give up some aero efficiency for a good looking car. Very few concept cars make it to production without some tweaks. Even if the Volt was super aerodynamic, they would still have to raise the roof to make it practical. as long as the car delivers on the promise of the technology and looks good, it will sell well.
Reply
Tim 11:00AM (11/14/2007)
Gentlemen,
When asked the question ““In April you were quoted as saying you were 90% confident the Volt would be produced. Considering interval developments, has that number increased?”
Mr. Lutz’ answer was a resounding “Yes”. He said GM is now “fully committed” to producing the car. He no longer considers the lithium-ion battery packs as the sticking point, the only issue now is systems integration.
That’s the important bit!! The batteries are no longer GM’s excuse!
Mr. Lutz goes on to say that the production Volt would not look entirely like the concept. The production model NEVER looks exactly like the concept and this car is almost 3 years away from production. The aero will be ironed out!
“One reason being that the concept performed very poorly when it was placed in the wind tunnel. In a memorable and humorous statement, he said “it would have done better if they put it in backwards”. Nonetheless, he said the car will be unmistakable in appearance as a Volt.”
Here’s more for you know-it-all armchair “scientists”:
http://www.gm-volt.com/2007/11/14/my-chevy-volt-question-to-bob-lutz/
Reply
GoodCheer 11:45AM (11/14/2007)
So they're going to "sacrifice" the styling to make this brick more aero? THANK GOODNESS!
I love the idea of a plug-in hybrid, and this has bumped GM up about 42 notches in my book (while Toyota has fallen quite a few for joining in the pissing about updating CAFE, for not dumping Panasonic in favor of a company that can make LiIon batteries etc.).... but (and I know aesthetics are very subjective) god I find the Volt ugly.
If Aptera can get to the point of being registrable where I am that's probably the direction I'll go for my next car, just because of the purity of the engineering (THAT's what I find sexy), but who knows, maybe the redesigned Volt will be a bit more palatable.
Reply
ug 1:38PM (11/14/2007)
Really it's a compromise between aero, weight, and battery pack size. Otherwise you would never have things like SUV hybrids, just pillbox cars. It's fine to have a less aero car as long as you meet your efficiency specs.
They are claiming 40 miles of EV range. They can make the body as anti-aero as they want as long as they can still deliver the range.
Reply
MikeW 12:43PM (11/14/2007)
I had a pinewood derby car that was teardrop shaped, that was accidentally ran backward by the stewards (in the arrowhead orientation) and went faster.
I think it was a weight distribution issue and not aerodynamics.
Reply
Snowdog 12:34PM (11/14/2007)
Yes this is a huge issue. We could increase fleet efficiencies dramatically with areo improvments. Hybrids don't get good econ on the highway because they are hybrids, they get it because they are aerodynamically efficient (Prius/Insight).
Of course many people don't like the looks of the Prius/Insight. But you can still have some style with the efficiencey. I don't mind the Prius and the Honda FCX is alright and presumably efficient.
Reply
Tony Belding 1:23PM (11/14/2007)
The Aptera doesn't look bad. It looks radically different, and strange to most people, and most people will consider that a turn-off. However. . . It wouldn't look radical or strange if car companies had been designing and selling aerodynamic cars for the last 70 years (since streamlining first was tried in the 1930s).
Many have commented on the resemblance between the Aptera and a small airplane. Airplanes are designed for aerodynamics. I don't see people all around grousing about how ugly most airplanes are. There's nothing ugly about an aerodynamic shape. The only difference is that we're accustomed to seeing that kind of shape on planes, not on cars.
Reply
OhmExcited 3:12PM (11/14/2007)
Simple solution -- put e-Flex in the Malibu as well. They would probably sell heaps.
Reply
Karkus 5:10PM (11/14/2007)
Why is Snowdog spreading his "hybrids don't get better highway MPG" myth again ?
Yes, the Prius and Insight are very aerodynamic, and that certainly helps highway MPG.
BUT...
look at the Camry or Civic or any other hydrid/non-hybrid comparison. The hybrid version always get significantly better highway MPG, and so obviously it's not just because of aerodynamics. The Civic hybrid is 46 MPG Highway, while the best non-hybrid civic is at 36 MPG.
1 A hybrid allows you to use a smaller ICE (while still having the same total system power), which means it will be more efficient. Period.
The Prius has 110 HP, for example, but it only needs a 76 hp ICE. This means it's more efficient at a constant highway speed load than a 110 hp engine car.
2 No highway is perfectly flat (or traffic speed constant), so there will be power demand variations. Any time that happens, the hybrid electric motor can balance out the load demand on ICE, keeping the load and RPMs more constant, which improves efficieny.
Again, the hybrid system wins. (and that doesn't even include regenerative braking on the downhills).
Reply
Snowdog 6:32PM (11/14/2007)
Geez, hybrid zealot much? I was not spreading an anti hybrid message, but a why not improve efficiency of all cars message.
At highway speed you really are not going to be putting energy into and removing it from the battery. When I hit the highway to visit relatives in another province, I have the car on cruise control for hours without interrupting it. Under these conditions a hybrid system is essentially doing nothing. I don't see a hill for hours either.
Highway advantages are insignificant and swamped by better aerodynamics, lower rolling resistance tires, optimized gearing. Most manual transmission cars don't even have a real overdrive, turning 3300+ RPM at highway speed.
An insight could be built to get 60MPG on the highway without batteries.
I have no problem with hybrids and they can make sense for a lot of people, but why not build an economy car with optimized aerodynamics, optimized gearing, low rolling resistance tires, weight savings, and a smaller engine.
What sound reason is there for only putting these simple fuel saving refinements only in hybrids? Why is no one building very efficient regular drivetrain cars.
Reply
Keith Rogers 11:17PM (11/14/2007)
Where did this NEW Volt picture come from?
Reply
Will 10:24AM (11/15/2007)
Dear Karkus,
The LS600 (hybrid) gets lower HWY mileage than the LS460. Both are completely embarrassed by Audi A8 diesel. Also, Car and Driver cited that their hybrid accord did worse on the HWY than the 4-cylinder Accord in their long-term test fleet.
A typical car's drag at HWY conditions consist of 80% aerodynamic drag and 20% drivetrain and rolling resistance. The Hybrid Civic has subtle aero tweaks to help distance it from the standard version.
The hybrids only get better mileage due to their propulsive architecture when it is in unsteady operation, stop-and-go. For steady state operation you don't need a 400lb battery pack increasing rolling resistance and a generator adding drivetrain drag.
Look at Big Rigs. They get up to 7mpg while towing 80,000lbs. If being a hybrid on long-haul trucks saved on operating cost (of which fuel is huge) then you'd better believe they would have switched years ago.
Reply
Chris M 8:05PM (11/16/2007)
Snowdog, the ones you term "hybrid zealots" have been fighting stupid anti-hybrid myths for so long it has become almost instinctive. The old "hybrids don't get any benefit on the highway" myth is one of the most persistant.
My own experience has shown that hybrids get excellent milage on the freeway, often better than city driving, contrary to what the EPA may say.
Will, comparing the LS600h to the LS460 isn't valid, the LS600h is a longer bigger car. Milage on the Accord hybrid isn't entirely relevant either, as that hybrid was designed mainly to improve performance.
As for "hybrids only get better mileage due to their propulsive architecture when it is in unsteady operation", I must point out that cars ALWAYS operate in an "unsteady" mode, no highway is perfectly straight and level, there are always fluctuations. Also, hybrids benefit from a smaller IC engine and a more constant IC engine power output and constant speed during highway travel.
Reply
why not the LS2/LS7? 4:30PM (11/18/2007)
Karkus:
A big reason the hybrid versions of these cars get better highway MPG is because they use low-rolling resistance tires. They are more optimized for economy, both by spending more on the vehicle and also by sacrificing performance (handling in this case).
They also swap the engines for smaller ones. This could be done without a hybrid system if people didn't insist that family cars do 0-60 in 7 seconds.
Reply
Azrael4h 5:08AM (11/19/2007)
Pretty much all vehicles on the road could have fuel economy improved by dropping the requirement to have a 280-400hp power plant in it.
Case in point, my Studebaker had an 85 gross hp motor, and could cruise easily at highway speeds. It had no issues driving with modern cars, other than 4 wheel drum brakes. My Cobalt may not be near as fast as it is, but I know it could do with about 50 less horse power and still be fine.
The new Malibu does not need a 260hp six to push it, cars of similar weight and worse aerodynamics were being pushed by 100 horsepower sixes which did just fine. It's the insistence on a higher level of performance so that drivers can get from one stop light to another faster that helps keep fuel economy stagnated.
Reply