what happened to Toyota's in-wheel motor in earlier concept cars?

If carbon fibre body frame is difficult for mass-production, that does not mean it is impossible. The level of automation is high in car manufacturing, so the labour intense production of such cars might be automated.

Which aspect doubles the efficiency of the the new concept cars with respect to the Prius? The weight reduction? Or the "plug-in" power-train?

i take your point about the automation of car manufacture though if you compare a steel/alloy panel that is pressed out in under a second compared to waiting for a carbon fibre laminate to cure taking several minutes you can quickly see why carbon fibre is only really applicable to low volume applications.

The 'doubling' of efficiecny seems to be a combination of the reduced weight, the downsizing of the engine to just 500cc (the prius is 1.5 litres) meaning that the electric motor take a bigger share of the load and also the plug in hybrid mode - though the latter aspect is clearly dependant on how much carbon is produced by the electricty generation at the power station.

Toyota recently announced that carbon fibre wouldn't be used in vehicles to reduce overall CO2 emissions, as the energy required (and CO2 released) to manufacture carbon fibre parts was greatly more than that required to manufacture steel parts. In short, fuel savings from carbon fibre did not repay the extra energy gone into making it (according to their calculations).

They did say that aluminium has a future, though, as the fuel savings for that did offset the extra energy of manufacture.

I agree that carbon fibre is unrealistic for a mass produced vehicle.

furthmore, manufacturers have to make their cars recycleable as they have to pay for the costs of their disposal - and a thermosetting plastic like carbon fibre is completely unrecycleable as it cannot be melted down.

Aluminium may require a lot of energy in the process of electrolysis to purify it from bauxite(aluminium oxide) but like steel and iron oxide, once it is in the metal state it can be recycled indefinitely.

carbon fibre is a great material for super light structures - (I myself have built a carbon fibre vehcile that achieves 4,500mpg) but it isn't practical for mass produced cars where issues of manufacturing speed, recyclablity and also impact resistance are issues

steel and aluminium tend to fold and buckle during a crash which is great at absorbing the kinetic energy - and away from the occupants. By contrast carbon fibre has a 'catastrophic mode of failure' which means that when it faisl it completly fails and disintegrates i. completly inappropriate for man carrying vehicles that have to pass strict safety tests.

No one has the bottom line on carbon fiber composites. Certainly, they have their drawbacks in the current state of the technology. But, the technology will develop, and the car of the future will probably be a combination of lightweight steel (or aluminium), plastic, carbon fiber composites and other materials.

As far as JC's comment about carbon fiber's 'catastrophic mode of failure,' a practical part can be built to withstand for more impact than a similar energy absorbing steel part. If the carbon fiber part fails catastrophically, it will be at an impact - no matter what the material - that no human body would survive.

Safety is a matter of design and engineering, as well as materials. Let's keep our options and our minds, open.

One third the weight + one third the engine power = 50% fuel consumption reduction or about 100 mpg.

Could better drive train + better batteries + reduced drag have driven fuel consumption to one third or about 150 mpg?

Aluminium is plentiful and since it can be recycled over and over again it is a very sustainable an appropriate product for car parts.

All the talk about Carbon Fiber composites being difficult to produce are partly correct. The material to be used in the 1/X is Carbon Fiber Reinforced Plastic, if on re-reads the article. Thus simplifying production. Some of the difficulties in carbon fiber production is the shape of the product. This 1/X frame will basically (I said BASICALLY) be plastic with Carbon Fiber rods running through it. These "rods" will come in only a few sizes and be simple round or slightly egg shaped straight "rods". Easy to mass produce, especially after the typical "new process" learning curve (which is currently under way).

The argument seems to have devolved into the equivelent of the discussion in the construction industry of:
plywood vs. oriented strand board

Plywood in general is strong and looks good.
Oriented strand board is fairly strong, doesn't look good, and is very very cheap.

By the way, in recent years, carbon fiber has both gotten much cheaper, and much stronger. This innovation has primary been financed due to the need for carbon fiber in wind blade turbines.

Is the "carbon fiber reinforced plastic" (CFRP) a thermoplastic or is it a thermoset plastic? There is a huge difference. Thermoplastic is recyclable, thermoset is not.

Standard terminology for fiberglass is to call it FRP (fiber reinforced plastic). Fiberglass is a thermoset composite. Are you sure that the carbon fiber is being placed in a thermoplastic? Every use I've seen so far for carbon fiber is in a thermoset composite.

Hi All,

The Fiberforge process uses a Thermoplastic matrix. So the resin is recyclable. Just melt the thermoplastic out in a nitrogen gas enviorment. The problem then is the fiber itself. Fiberforge is using Victrex PEEK (PolyEtherEtherKetone). Which is a tough plastic. Machinists in the company I work for try to avoid it. Adding the fiber makes the part tough and strong.

The parts are formed with simple vacuum die tools while the Thermoplastic is in a plastic state. The Carbon Fiber is embedded into plastic by being squeezed inbetween sheets of thermoplastic.

They say the process is cheaper than steel bodies up to several tens of thousands of units. Because it avoids the needs for large steel stamping equipment and the very expensive, hard to make, machined hardened steel stamping dies.

The question has to be asked WOULD we have millions of scrap Cabon Fiber car bodies? If the stuff does not rust, maybe one would come in to a dealarship and just have the running gear and drive train replaced. The thermoplastics being used are quite durable, compared to what was available only 30 years ago. Keeping the paint intact (to avoid UV damage) would be much more important with such a car body, however.

What I do not like about this Toyota design is all the clear panels. Is this not all about Green House effect? That design is a rolling hot-house! Put a insulated roof on it!

If the carbon fiber reinforcement within a thermoplastic matrix is pure carbon fiber without thermoset resins or fillers, then it could be possible to look at recycling the carbon fiber from a different perspective. (The thermoplastic component is no problem.)

If structural members could be standardized within the industry, reuse (after inspection) of structural carbon fiber into new product could be possible. This would require a paradigm shift in how we design and manufacture.

Carbon fiber is very fatigue resistant. It has the lowest loss of strength through millions of flexing cycles of any common structural material. Ironically, the next best material for fatigue resistance is wood. However, when it fails, there's no warning. There would have to be sensors built in to give warning of micro-cracks.

Yeah, all that glass is a problem. That long, low-sloped window is also unnecessary. The Daimler bionic boxfish project has shown that a coefficient of drag of 0.19 can be achieved with a blunt front and boxy shape. It's the rear of the car that is most critical for reducing drag.

If the carbon fiber and thermoplastics were being produced from biomass feedstocks, would recyclability really be a problem?

At worst, you pyrolize the old bodies and turn them into liquid fuel...

McLaren/Mercedes seems to have worked out a workable solution for front crash structure, their SLR is made from CF, "Mercedes-Benz exploits these qualities by incorporating two 620-millimetre longitudinal members made from carbon fibre in the front structure of the new SLR. These absorb the entire energy of the crash in a defined head-on collision, leaving the passenger cell largely undamaged." - http://www.seriouswheels.com/cars/top-Mercedes-SLR-McLaren.htm

In addition, World Rally Championship cars use carbon-fiber door plates for occupant side-impact protection. They seem to work pretty well.