Impressive aero attention to detail

Well, that jibes.... the Volt is much heavier, and should coast downhill faster.

Thanks for the replies, Folks.

 

On the mentions of drafting, just don't do it.

Besides, if your Cd is 0.24, it's not going to help as much

Series of Articles About Hypermiling | PriusChat

Got a 2007 Prius in January and one of the potential projects is covering the underside with coroplast like Aerocivic - Honda Civic modifications for maximum gas mileage - aerocivic.com.

Since it's an election year, there are plenty of campaign signs to get - they are made of coroplast.

got a question.

A few people have put boattails to the end of their cars to improve the aero, but it's not practical on a Prius as it would be too long.

Thought I saw something on the Chevy Volt to have side spoilers or something around the taillights, to control the Kamm back drag better...wondering if there is such a thing and if so how it works?

 

I think you're referring to the sharp cutoff on the rear, referred to as "aero-corners" by some manufacturers. The purpose is to delay wake formation by inducing separation of the flow off the back, creating a short "phantom tail." The 3rd and 4th gen Prius already have this feature, more pronounced on the 3rd gen bumper cover, and less visible on the 4th gen because it also forms the edge of the taillights for most of the car's height.

Also, the Prius isn't too long to put a tail on, depending on one's situation....

 

One detail almost every car journal left out when reviewing the CLA is that the American model, the CLA 250, has Mercedes--claimed Cd .28 (only the CLA 180 BlueEfficiency, available only in Europe, claimed Cd .22). See here and here.

 

That's only 20 counts higher than what they claimed. Meanwhile the Leaf, for which Nissan also claims Cd .28, returned Cd .32 in the same test.

 

Don't forget Honda; in this tunnel, the Insight returned Cd .30 (claimed .25).

That said, there may be things going on here that impacted the results. Every tunnel behaves differently, as you know, and the A2 that Car & Driver used is very small-section and has no moving ground, perhaps skewing the results, while Mercedes' tunnel looks like this:

While independent tests are a good thing, the organizations conducting them often don't have access to the same kind of resources (and resulting accuracy) as the OEMs, and I think the better use of this C&D test is as a comparison of relative Cd between cars rather than absolute (the Prius' Cd here, for instance, is 4% higher than Toyota claims, while the Mercedes' is 7% higher; put another way, this tunnel showed a 15% difference in the two cars' drag coefficient, where the manufacturers' numbers indicate one of 12%. The resulting numbers would probably be different again if we put both cars in Mercedes' tunnel and then both in Toyota's).

I wonder if C&D will continue doing tests like this (I hope they do), and when we'll see the 4th gen tested.

 

A single, least significant digit is in the noise range. If it had been off by more than one digit, there would be a problem. One digit out of 25 is 4% with some tolerance above and below.

Bob Wilson

 

I own all 3 plus driven them over 10,000 miles those are my real life experiences!