[Captain Awesome]

Originally Posted by Number 3

Most of the composites you are thinking of have one big benefit and that is low tooling costs. A door inner panel for example would take 5 dies to make it from steel or aluminum (4 if you are lucky, good or both). And aluminum isn't cheap either so that is also one of the reasons composites (plastics) are favored on low volume applications like Corvette or special runs vehicles.

Tooling costs can be spread out over a large volume of cars if they sell a lot of them, which is the point of the discussion. In order to meet the draconian CAFE standards, they will have to use exotic materials in ALL cars. So, that means volume production and the tooling costs become much less significant.

Remember that composite tooling costs less, but the fabrication process is a lot more complex, so this offsets some of the tooling advantages. It takes a lot less time to stamp sheetmetal than it does to cure composites, which often need to be made in a vacuum and cured in an autoclave and possibly heat treated as well.

The CF materials used in the automotive applications won't be sensitive to fatigue. They are in fenders or roof panels that aren't stressed very much. In the Boeing Dreamliner though, the CF is structural and that may be what caused the brief recall.

What you are talking about is current applications for carbon fiber. Essentially, it is mostly used as a decoration or a "high tech gimmick". If you say it's made from carbon fiber it impresses people more and if you expose the weave people "ooh" and "aah" at it, in spite of the fact that it is nothing more than a cosmetic thing. These uses of carbon fiber are not saving any fuel, or making the car significantly lighter or stronger, because they are not replacing heavy structural items with carbon fiber.

A good grade of fiberglass can get close to the tensile strength of carbon fiber with just a slight increase in weight. This could easily replace carbon fiber in fender wells and roof panels and would save a lot of the cost, it just wouldn't be useful as a "shiny thing" to make people buy the car.

You are absolutely correct in your point that they won't pay for themselves, at least in my opinion. Many of the OEMs as well as the dealers this past week have been telling us that the high cost of FE will drive many people out of the market costing millions of sales per year.

I saw an interesting article in one of the business sites this past week that said that the gov estimates for meeting CAFE put the cost at $3300 per car. This is going to cost a lot of sales because they said it would put the ability to get a car loan out of reach of (I believe they said) 17 million families. Since we know that it is in their best interest to paint the least damaging projection possible, I believe that the costs of a new car is going to be much higher than their predictions.

So back to the original point on the Mustang weighing 300 pounds less sure it is possible. With downsizing and clever engineering it should be no problem. And if you do it well, you can make a car smaller and maintain a roomy interior. The 3 Series is a good example of that. I think they actually made the new one a little bigger and still cut some weight out over the previous model. Look at the weight of the Hyundai Sonata, I think it's about 3200 pounds or so and yet it is roomy and does a lot of things very well.

From my experience there are a tremendous number of ways to get the weight out of existing cars in simple ways. For example, the plastics used on interior pieces could be reduced in weight or replaced with something lighter or removed completely by restyling the dashboards. There's a lot of bloat in the wiring harnesses we use as well. They could reduce the size of all the wiring by using a bus system for signalling devices and also stepping up to a higher voltage system.

Just watch out for the weight savings that comes from simply having a base 4 cyclinder engine. That alone with the smaller transmission you can use and the smaller axle can result in a good chunk of that 300 pounds.

This is the exact thing I do not want to see. It bodes very badly for V8 engines when people start thinking they MUST save weight to meet some arbitrary economy number pulled out of the air by someone who doesn't even own a car.