2013 GM Malibu aerodynamics

[California98Civic]

Okay. This is way-cool. But are these claims all believable? Specific claims like this from another modder or from someone hawking a product on this site we would all rightly question. What about with Chevy? How do they arrive at these figures? Recently Ford claimed better aero for one of its vehicles than, I think, the Prius, but their Cd number for the Prius was different than Toyota's (higher, surprise surprise). Such variation raises the question of the "objectivity" of industry self-reporting of these results and how they may be manipulated for marketing, no?

[gone-ot]

...good point, so is it: (a) real propaganda or (b) ficticious propaganda?

[euromodder]

Originally Posted by tjts1

Does anybody else find the 0.35 of the old malibu and 0.29 of the new one pathetic?

If that's 0.29 for the ECO version, it's really pathetic.

[CigaR007]

Originally Posted by California98Civic

Okay. This is way-cool. But are these claims all believable? Specific claims like this from another modder or from someone hawking a product on this site we would all rightly question. What about with Chevy? How do they arrive at these figures?

Those figures seem to be in check. My hunch is that such figures are backed by a methodical and scientific process, except that the Cd of .29 is deceiving considering that 15 years ago, the Passat IV had a Cd of .27, without the implementation of such mods.

[Frank Lee]

Originally Posted by California98Civic

Okay. This is way-cool. But are these claims all believable? Specific claims like this from another modder or from someone hawking a product on this site we would all rightly question. What about with Chevy? How do they arrive at these figures? Recently Ford claimed better aero for one of its vehicles than, I think, the Prius, but their Cd number for the Prius was different than Toyota's (higher, surprise surprise). Such variation raises the question of the "objectivity" of industry self-reporting of these results and how they may be manipulated for marketing, no?

Wind tunnels are like dynos; each one gives a different reading.

That said, I'd believe the claims of an outfit with a windtunnel(s) and a staff of professionals running it over... well... anyone else.

[jime57]

Originally Posted by euromodder

If that's 0.29 for the ECO version, it's really pathetic.

Well, I think one must put this is perspective. The stars, the Insights, Audi, and Prius, are slightly better. But it seems to me that .29 is a pretty good number for a large family sedan which must meet a broad audience. Lets give them a little credit. At least they are honestly trying and lets give them some credit for that. It doesn't seem pathetic to me at all

I was surprised that they gained fewer points working the rear of the car than the front. That is counter to much of what we here believe.

[California98Civic]

Originally Posted by jimepting

I was surprised that they gained fewer points working the rear of the car than the front. That is counter to much of what we here believe.

Me too. If we believe their numbers, there's quite a bit to be gained up front. Though in fairness, nobody here really argues that there's nothing to be gained up front, just that there's more in the back.

[tjts1]

Originally Posted by jimepting

Well, I think one must put this is perspective. The stars, the Insights, Audi, and Prius, are slightly better. But it seems to me that .29 is a pretty good number for a large family sedan which must meet a broad audience. Lets give them a little credit. At least they are honestly trying and lets give them some credit for that. It doesn't seem pathetic to me at all

The larger and longer the car it easier it is to get a very low CD number. 0.29 in a small hatchback is a lot more impressive. 0.29 in a large sedan is pathetic.

[Cd]

Originally Posted by jimepting

Well, I think one must put this is perspective. The stars, the Insights, Audi, and Prius, are slightly better. But it seems to me that .29 is a pretty good number for a large family sedan which must meet a broad audience. Lets give them a little credit. At least they are honestly trying and lets give them some credit for that. It doesn't seem pathetic to me at all

They brag as if .29 is something extraordinary. GM pulled a .29 ( point .299 to be exact ) from a 1989 Grand Prix.

The Lexus LS430 is a full size family car, yet gets a slick point twenty five drag coefficient.

Seems to me the guys at GM aren't trying very hard !

[jime57]

Originally Posted by Cd

They brag as if .29 is something extraordinary. GM pulled a .29 ( point .299 to be exact ) from a 1989 Grand Prix.

The Lexus LS430 is a full size family car, yet gets a slick point twenty five drag coefficient.

Seems to me the guys at GM aren't trying very hard !

Well, I thank that Frank said it best. "Wind tunnels, like chassis dynos, deliver different results in different hands," (i.e. particularly when marketing is involved - I'm giving GM a bit of credit for publishing a numer that I find credible. (BTW, I'm very well informed on chassis dynos.) Aren't any of you guys suspicious enough to recognize that a corporate marketing types just "might" set up some really good numbers for his car, that an independent organization could not duplicate? Tell me just how you would know?

When I look at the Lexus you picture, I don't see .25, given Hucho, Phil, and the general tone of the discussion here. I don't doubt that Lexus quoted the number, but having done some tuft testing on the rear of my Gen1 Insight, I can feel pretty darn sure that the flow on that back window is DETACHED. I can't see the actual contours very well from this picture. It would be nice to have plann&profile views. Apparently some manufacturers gain a bit by tapering the rear plan view. Can't tell whether Lexus did that.
Anyway, I'm done with it. There is no genuine independent information available, that I am aware of, and relieance on manufacturer's claims is highly questionable.


This a circular, and largely useless, argument. Non of us have any factual independent information on what the real Cd would be on any of these cars. There are numerous opportunities to distort the data, in this day where simple single numbers prevail.