GM: Chevy Volt's Cd is 0.28, Prius is 0.30 (tested in multiple tunnels), EV1 is 0.21

[Silveredwings]

GM's perennial efforts at ever more convincing marketing sound bites never makes up for their reputation. I've learned that the most optimistic I can be is to say "we'll see."

[majestic]

I think GM is right on with these numbers.

Comparing different cars in the same windtunnel is the only way to get an accurate comparison.

It is also reasonable that the larger tires on the Prius V add atleast 30 counts of drag, based on data from other manufactures.

This means the base Prius would be .27 compared to the Volts .28, as tested in GMs windtunnel. Meaning the Prius would stiil be the most aerodynamic choice.

Also, where is the statement from Toyota? Anybody find one?

As far as the EV1 goes, the difference in drag is probably due to the new testing standards, that include rolling wheels and a simulated moving road. I don't think anybody was using those back in the 90s.

[RobertSmalls]

Originally Posted by majestic

Also, where is the statement from Toyota? Anybody find one?

Until Toyota gets a Volt in their wind tunnel, their best course of action is to not even acknowledge GM's marketing shenanigans.

Which gets me thinking, wouldn't it be more fair to compare the 2012 Volt against the 2012 Prius, not the 2010 Prius?

But anyway, the Prius has a lower CdA than the Volt, so it wins in a wind tunnel.

[aerohead]

SAE Paper # 830301,Comparison Tests Between Major European and North American Wind Tunnels,by Dr.Rolf Buchheim,Volkswagen AG.
Buchheim is one of Hucho's partners in crime.

[donee]

Hi All,

The EPA may have a new test methodology, they are talking about. Remember, the main reason the Car companies make these measurements is they are required to by the EPA. Why? So the CdA factor can be dialed into the dynamometer settings to simulate air drag in the mileage/polution testing.

Its quite probable the EPA now has Yaw conditions required for the testing, and then they average the whole thing down to some confusing combination of straight and twisted air drags. Kinda like the EPA does with the highway and city mileages...

[MetroMPG]

Originally Posted by majestic

Also, where is the statement from Toyota? Anybody find one?

Nope:

Newsroom : Our Point of View / Toyota

They're too busy with the floor mat/unintended acceleration issue at the moment, I think.

Maybe they'll respond though... Toyota was quick to jump on Ford when they started trumpeting the Fusion hybrid as the most efficient mid-size car in North America. Strictly speaking (per EPA), the Prius is a mid-size car, and it's more efficient than the Fusion. So Ford changed its marketing to say "mid-size sedan."

I've said it before: in the big picture, the absolute numbers are less important than the fact they're competing over them. Lower! Lower!