Jeremy Cato writes another article about aerodynamics. Misinformation ensues.
 

We recently roasted Jeremy Cato, The Globe and Mail's chief auto writer, for praising the 2010 Camaro's 0.37 coefficient of drag as "pretty slick" (see http://ecomodder.com/forum/showthrea...-0-a-7741.html ).

In today's Report on Green Solutions for Earth Day, Cato attempts to parlay his "knowledge" of things aerodynamic into general article about how automakers are increasing efficiency in the wind tunnel.

How to stop being a drag
Auto designers are finding that sharp edges can be just as aerodynamic as smooth curves

Here's a doozy of a quote:

What he fails to mention however are the actual figures:

http://www.zercustoms.com/news/image...dynamics-b.jpg

Ford Flex: 0.355 (source)
Chevy Traverse: 0.33 (source)

http://image.automobilemag.com/f/gre...se-driving.jpg

If the Flex gets better fuel economy than the Traverse, superior aerodynamics apparently isn't the reason. (Note: I don't know the reference area for each vehicle, so it's possible the CdA of the Flex could be less - but that's not a wind tunnel achievement, which is what the article suggests.)

The entire article isn't horrible - in fact, I'm happy to see the importance of aero being discussed in the mainstream press - but Cato doesn't do his homework (inexcusable, as the chief auto writer for Canada's biggest newspaper). And it bugs me that as a result, there are undoubtedly people out there this morning saying, "my, my! I didn't realize the Ford Flex was so wonderfully aerodynamic!"

Which leaves me skeptical about this other potentially interesting tidbit he relays:

Of course you can't comment on the article... hah.


edit: there is a button to send a letter to the editor at the bottom though

"as aerodynamically efficient as possible"... is this guy a journalist or a marketter? Is he being paid directly by these people to write articles about their cars? It strikes me that he is throwing away the term "journalistic integrity" with every article that we see here on ecomodder.

Is it possible that the total drag (CdA) of the ford is better than the Chev? Either way, they both suck.

Someone send him a link to these threads for his amusement :) We'd gladly help to educate him.

It could have less drag overall but as I think metro said it would have alot more to do with the frontal area of the car(wheel base on the Ford might be a hair narrower) than with its aero properties as the traverse is obviously more aero friendly in shape.

But he says SHAPE. The shape is not more aero. < is aero, C is kinda aero, I. . .not aero.

If the volt were aero as possible it will look like a rain drop and have polymer riblet adhesive applied over its outer-layer of paint that will make it look funny. I feel like its going to look alot more like a Camaro than a rain drop. . .and I feel like its going to have shiny glossy paint rather than a matte polymer over-top of its paint.

If you squint at the Volt, you can see a Prius / Insight shape in there. There's just some 'styling' to make it look different.

-grabs PM's shoulders and shifts to point in a new direction- you were looking at the 2010 Prius. The brick is the volt.

Lol. :d

Here's a perfect picture. The back end of the Volt is a hatch, just like the prius. They made it look like a sedan, but it's not.

http://www.gm-volt.com/o/volt_prius.jpg
http://farm4.static.flickr.com/3399/...248030dfa7.jpg

That's because I only link the lousy ones. :)

He's capable of producing some decent articles. But stuff like this just makes me cringe.

Maybe I'm just missing the distinction: perhaps he's not a "journalist", he's a "reviewer". One supposedly presents issues, the other delivers an opinion.

But delivering factual errors with your opinion is still a bad idea!

lawls... I bet the mirror design shaves 3pts off the cD

That's a funny, yes?

Just checking.

Partially but the part quoted was not the joke.

The riblets actually do decrease drag, but the funny was that if its as Aero as possible it will be matte whatever color because the film will make it not glossy. It would make it look like a "3-d" image plate that has several images imbedded, instead of sleek and glossy.

I'd be more than happy to explain either in a different thread or in a message if you're interested. I mentioned it partially in the artificial feathers thread under aero, but I don't have the link handy.

For the same reasons that golf ball type dimples won't do anything useful on the body of a car (because it already has a turbulent boundary layer, not laminar flow which can be "managed" by small surface imperfections), I doubt "riblets" will help either - but I need more information to know just what you're referring to. I'll go check the feathers thread so this one doesn't veer off-topic.

back end
 

If I were on a controlled substance,and looking at the two cars only from the B-pillars back,aside from the color difference,there'd be very little to distinguish one from the other.And in this sense,that's not a bad thing!Thanks for the pics.

I guess they pointed out who they were marketing to putting the volt in a driveway that has the grass-strip in the middle.

Aerodynamically they aren't even close. The frontal area of the Volt is enormous, while the prius is pretty normal. If they really wanted to make it even more aero the nose would be longer like the Prius or the Murcielago.

Define "enormous" please.

My understanding is the Volt may be slightly smaller than the Prius, which implies a smaller projected area.

They're very close in size:

Prius 3 width = 68.7 in; height = 58.7 in; w*h = 4033 in^2
source

Volt width = 70.8 in; height = 56.3 in; w*h = 3986 in^2
source

(Obviously not a calculation for projected A, just a relative comparison of the product of their dimensions.)

Apparently not so enormous. I knew it wasn't much taller(its shorter than I expected and than the older. . .tank looking mdels projected) but I thought it would have been wider than the Prius. I was pretty sure the Prius was narrower than the Del Sol, but I guess I was incorrect.

I should have known as the Prius is qualified as a mid-size(?)

The Volt in my mind was this http://image.automobilemag.com/f/gre...ept_design.jpg.

I may need to reconsider my original write-off as it would seem they have scaled back from the Camaro "green" counterpart.

Yeah, that original concept looks more like the Camaro than the current version Volt. I'm not sure what was going on there. ???

They still had no clue what aero was then. Now they kinda do, or they are getting closer anyway.

It wasn't designed to be produced when they came up with that concept. They realized the good press of building it afterwards.

My understanding is, the back end of a car potentially has more effect on the overall c/d than the front (unless you go drastic in front, with a long slope like basjoos). We don't have a really good view of the back but I can see the final cross sectional area is still pretty big. That's what determines the overall size of the wake, correct?

As for the rest - if they really want to drop the c/d, the car needs a full belly pan. But they don't get 'cool' or bling points for that so might not do it. Would be a shame to not treat the underside though; it should be cheap to build and no 'styling' penalty for using an optimum design.

The new Prius does in fact have smooth belly panels. GM should definitely take notice.

Actually, some people furiously argued that the mirrors were not causing drag at all. So they must have been shaving points to compensate for their area...

Not that I believe it's the case though...

Correct, assuming attached flow to the cut-off. It's not significantly different than the Prius rear end.

If they have in fact managed to beat the Prius 0.25 figure, you can be sure they have paid attention to smoothing the underside. The bottom of the Volt's battery pack itself will be flat, and it occupies a significant amount of the underside real estate.