Looking for outstanding efficiency numbers

[Ernie Rogers]

Hello, guys,

I have a favor to ask--

Today, I am embarking on a great task--beginning of a "white paper" on the potential for greater efficiency in cars. This is for the Sierra Club. I see the matter as logically divided into four or five parts--

1. Aerodynamics
2. Rolling resistance
3. Power plant efficiency
4. Other losses such as accessories, bearings, lubricants, etc.
5. Future prospects outside the paradigm such as pavement
types and modes of car use.

The Sierra Club folks currently are hoping to get CAFE, the "corporate average fuel economy" required for U.S. cars, up to 55 mpg by about 2030. I think they are setting their sights WAY too low. So I am putting together information showing what has already been done, and what we can expect in the near future.

Guys have already responded on the aero list with lots of samples of super-low drag coefficients. Now, I'm proceding down the list.

The tires on my car did about Cd = 0.0065 at 40 psi. (205/60R-16 Michelin Energy MXV4 S8) Well, we know 0.0060 is doable today. But, what are the solar and supermileage cars doing for rolling resistance? Anybody know of lower numbers?

Any other citations on efficiency of components besides tires are wanted too.

Ernie Rogers

[dcb]

Why the Cross post Ernie? Ask a moderator to move it here if appropriate, but please dont fracture the discussion.
Great forum, asking for help

[NeilBlanchard]

Hi Ernie,

I have written what I think is a comprehensive outline for just such a thing:

More ways for auto makers to build more efficient vehicles - Updated 3 April 09! - Vox

Also, I have made a list of cars to understand and mimic:

Cars to Emulate and Study - Vox

[SVOboy]

I don't know the specifics offhand, but do you have the time to go about contacting builders of solar cars and such individually? You could just find the shell eco-marathon competition list and call up some of the top contenders and ask them for details.

[Ernie Rogers]

Originally Posted by dcb

Why the Cross post Ernie? Ask a moderator to move it here if appropriate, but please dont fracture the discussion.
Great forum, asking for help

Okay, help me get this right. Here is what I think I did--

I asked the Aerodynamics list for examples of very low Cd numbers, indicating that was part of a greater task I was working on. I thanked them for input, and said I would repeat the question under general efficiency for answers on the other items.

Then I posted here, asking for specific info on very low rolling resistance tires, and again showing how it fit into the overall task.

I guess I split my query into two places because it seemed to logically have two homes.

What shall we do? Should we move the aero discussion to here?

Ernie Rogers

[Ernie Rogers]

Thanks, Neil,

I read your two articles. Very good work and pretty thorough.

Ernie

Originally Posted by NeilBlanchard

Hi Ernie,

I have written what I think is a comprehensive outline for just such a thing:

More ways for auto makers to build more efficient vehicles - Updated 3 April 09! - Vox

Also, I have made a list of cars to understand and mimic:

Cars to Emulate and Study - Vox

[trebuchet03]

Tires used in super mileage competition....

Michelin makes a special tire in France for the eco-marathon races (these aren't available to the public, not easily at least). It's clincher bike tire but, it's a radial ply. Crr is claimed to be .001 (1kg/ton) and if I recall inflation pressure is somewhere around 50psi (as opposed to a skinny road bike tire which is >100psi).

The tires are super light and super flexible, but VERY susceptible to puncture. I'm not 100%sure of the name, but I've always seen them referenced as eco-marathon radials. They're identifiable by their wide rolling surface and light blue sidewall (http://web.student.chalmers.se/group...Eco08/Eco6.jpg - random google picture with them)

[NeilBlanchard]

Hi,

On the tires, what I listed in my blog was we should use metal wheels with solid treads for the lowest rolling resistance possible, and then tune the suspension accordingly. The hydraulic pressure developed by the suspension should be used to generate electricity (a la what MIT has done). So, we gain in efficiency and regain some of what would have been waste energy, as well.

[superchow]

Two things come to mind when reading your initial setup:

First: Greater fuel savings can be achieved when suggesting a minimum CAFE mileage for all vehicles. At 15,000 miles/yr going from 20 to 25 mpg saves as much fuel as going from 40 to 66.6 mpg. Imagine all pickups and SUVs on the road averaging 25+ mpg... Isn't it the reduction of oil dependency/consumption that we are striving for?

Second: I see no mention on driver education. We all know that one can quite easily improve mileage without any physical modifications by 20%-30%, all by just changing the way one drives.

All that being said, a big thumbs up ( ) for dedicating time to writing a white paper on these issues.

[dcb]

Originally Posted by Ernie Rogers

Okay, help me get this right. Here is what I think I did--

My bad, I'm slow.