They should look at safety through deflection of the passenger cage rather than safety through the attempt to overcome the energy of the colliding mass. Go to Google Patents and look at patent number 6601873.

....wherein the deflecting surfaces are deflecting ramps directed diagonally downward, said deflecting ramps being adapted to lower the wheels, upon the collapse of the crumple zone, below a floor of the motor vehicle in a direction of the passenger compartment....

what about Rocky Mountain Institute's Hypercar - now Fiberforge company spinout? RMI's been talking about the benefits of lower vehicle weight for years - why hasn't a major company partnered with Fiberforge to make advanced-composites part of vehicle bodies?

What I've read about the holdup on Fiberforge technology for car chassis is that materials are still deemed 10-20x as expensive as steel, and Detroit is already sucking wind on margins because of pension costs, so they just don't go there.

That said, Fiberforge makes it sound like you could design a car with far fewer pieces, thus reducing the labor component of your building costs...pretty cool for a US-based manufacturer with higher labor costs.

Picture, if you will, a mid-size car that saves 800 pounds using Carbon fiber, with 10 Mph bumpers, and an eestor energy storage unit driving 4 in-wheel electric motors. Seems like it could get you to 100 mpg equivalent.

Assuming $3/gallon gasoline over 10 years, it should save the owner more than $8,000.00 in "fuel" costs compared to a 35 mpg vehicle.

I'd like to think that Detroit could crank out millions of carbon fiber chassis at a reasonable cost, if they just invested in the capital equipment to mature the manufacturing processes.

Additional thoughts on the relationship of size, weight, and safety...

Part of the size-safety relationship is that larger crumple zones equate to greater safety. The downsizing of vehicle weight in the 1970's and 1980's usually involved downsizing the crumple zones as well. With advanced materials reducing weight, it is still quite possible to maintain or increase the vehicle's dimensions to maintain generous crumple zones.

There are some concerns that carbon fiber is stiff and strong...until it shatters in very high energy collisions. This could be offset somewhat by dispersing the impact with springs/shock absorbers/high-strength steel sections as the first lines of defense beyond the carbon fiber chassis. Used judiciously, it should still be possible to substantially reduce overall weight while increasing safety.

The safety/weight thing is one of those Great Lies that the oil companies and Detroit love perpetuating. That's like saying football is dangerous the smaller you are. What they fail to mention is that they're assuming one plays in the NFL.

Weight, in and of itself, has nothing to do with safety, and in many ways can compromise it. Take one vehicle with a big front engine hitting a stationary object at 30 mph. Now take a well-designed ultra-light vehicle going the same speed, with the driver restrained properly and with all the modern safety bells and whistles, but without the big engine in front. Guess who's more likely to walk away without a scratch?

Single-vehicle crash data show absolutely no linear relationship between weight and safety.

Formula 1 cars are light and very strong, and in fact have to have ballast added to get them to minimum regulation weight, I agree weight has little to do with safety or strength, but if you add cost constraints and engineering imagination, there is a viable solution out there.

After all we are only looking for 4% fuel economy increase a year, and stable or improving safety, neither of these is a stretch

"assuming $3/gallon gasoline over ten years" You're dreaming healthy breeze. Even the IEA say we are heading for a supply crunch in the next five years. Peak oil means that the happy motoring wonderland is coming to an end.

Incremental changes will prove pointless. We have to completely change the way we think about personal mobility starting now instead of worrying about how we can get a hybrid SUV to tow the power boat to the lake. We should put massive effort into development of EV's and even if we do that well enough our wasteful ways will have to change.

Saftey is more than colision performance. For example, in a Chicagoland suburb a year or so ago, the new ower of a full sized Dodge pickup was killed by the dealership porter delivering the vehicle to the front of the dealership. The truck was backed right into the guy, killing him in front of his son.

Here the parochialism of Americans is the problem. Here in Europe we have cars that are both very safe and very fuel-efficient. Is it a coincidence that we do not have as many gas-guzzling SUV's? I think not. You cannot violate the laws of physics, if you want to drag around 5000lbs of unnecessary weight this will inevitably take more energy than a sensibly-sized saloon car. As for the supposed relationship between mass and safety, look at Volvo; they have had the safest cars in Europe for as long as I can remember, and their range in general is not much heavier than any other manufacturer.

Patrice Leboeuf,

Americans and Canadians have been mislead (by the local Big-3) for decades in falsely believing that (bigger + heavier = safer).

The main reason is that the local Big-3 cannot economically produce high quality smaller vehicles. When they tried it was a fiasco, so they had to turn to Asia for production of smaller vehicles. Unfortunately or purposely (a strong possiblity) the small vehicles they imported were not much better.

It is not a suprise that the locally produced vehicles (cars) went down from almost 100% to less than 40% in the last 3 or 4 decades.

The production of huge gas guzzlers was a way to keep the production and the plants going.

The sell all those gas guzzlers they had to convince us that Bigger + Heavier = Safer.... and too many of us believed them.

Of course, smaller, lighter cars can be as good (if not better) and as safe (if not safer). They certainly consume a lot less fuel and create a lot less pollution. Many of us are starting to see the light and understand that we've been brain washed with smart PR.

Small but well-designed vehicles can be very safe if they don't get hit by larger vehicles, and vice versa. Unfortunately, somehow the reptilian part of our brains kept up the vehicular "arm race", that wants safety at the expense of others', and thus vehicles got larger and heavier. And yes, the same reptilian brains drive up the horsepower race, as well. It have got to stop somewhere.

The issue of size and weight come to the fore in multivehicle crashes. Data indicates that in a vehicle with less mass, the occupant's interaction with the vehicle is more damaging. The bottom line is that in average American traffic of today, vehicles that weigh less than about 2900 pounds are less safe than heavier vehicles. However, in a sedan with full air bag protection that weighs at least 3600 pounds, you are as safe as you can be, based on vehicle mass, because the data shows not further improvement in safty for the heavier vehicles. Basically, if buy something heavier than a Camry Hybrid, you are just wasting gas and increasing the hazard for those driving smaller cars.

Should we have dedicated (right?) lane or truck roads for large trucks, 4 x 4's, large pick-ups, motor homes and similar monsters above 3500 lbs?

Smaller vehicles (3500 lbs and below) would have all the other lanes and roads.

(Some drivers may have to be restricted to dirt roads ONLY)

Air traffic, where (commonly) separated by aircraft weight is much safer.

Americans have a 50% higher automotive death rate per passenger mile while using up nearly twice as much fuel per mile. Auto safety is not only about big vehicles hitting small vehicles. If that were the case we would all be driving semi tractors.

The essential problem is automotive morphology. Our vehicles are grossly inefficient from a space, materials and fuel utilization standpoint. Average ridership here in Minnesota is 1.11 passengers per vehicle. What this means is that on average we are using a 4,000 pound machine to move a 200 pound payload, while we are rapidly running out of fossil fuel and cooking the planet to death. This is not sustainable.

We buy a vehicle based on its ultimate load and then use it very lightly loaded most of the time. We tend to use the wrong tool for the task, for example, buying a pickup to pull a trailer six times per year and then commuting in that vehicle. One should lease the pickup when needed and commute in a more appropriate vehicle. If we had European driving habits we could nearly eliminate oil imports.

It's the operation and efficiency of the whole system that counts. Hydrogen fuel cells are efficient, but hydrogen fuel delivery systems are extremely inefficient. Plug-in hybrids will result in a large increase in coal-fired power plants which put out twice as much CO2 per unit of energy delivered as petroleum. Vehicles need to be recyclable, which eliminates thermoset composites like carbon fiber. Eastern Europe's Trabant fiasco should have taught us something about that. Fuel cells and an exponential increase in batteries would also be recycling nightmares.

We need ride height standardization so that heavy vehicles don't place their mass at small vehicle passenger compartments. Constant-height hydraulic suspensions could accomplish that.

For the present, smaller, more aerodynamic IC-driven vehicles made from steel are the most achievable technology. Three vehicles show the way: the Smart fortwo with its Tridion safety cell roll cage, the mid-engine Mitsubishi iCar, the Mercedes "boxfish" Bionic Project car. No engine in front simplifies design of energy absorbing front; underfloor mid-engine lowers center of gravity; four seats is sufficient for 95% of driving needs; small turbo-charged engines with moderate power/weight ratios improve efficiency; excellent aerodynamics can be achieved with blunt ends and rectangular form. All that's needed beyond this is energy recovery and fuel economy could be quadrupled for the entire automotive fleet.

We need a 7-year plan to send all present day vehicles to the crusher. This would revitalize our auto industry and pump up the economy. There's nothing like stress to bring out innovation. If we're still driving 4,000 pound vehicles 20 years from now, we will know we have failed.

Oops -- first sentence should read Americans have 50% higher automotive death rate than Europeans.

Hi Mr. Schumacher Audi did built the Car you propose in the Year 2000 . The prius2aboutequalsize the Audi A2 1.2 with 81 G CO2 per KM against the 104 G of the Prius2 . But they closed the Production because at that time the fuel price was to low and too few people bought that car . Now as a used car it is very high valued .

Hi Mr. Schumacher the worldrecordholder in fuel-efficiency ( aboutprius2equalsize Audi A2 1.2 with 81 G CO2 / KM against the 104 of the prius2 )was made from Aliuminium which is more energy efficient than Steel if you include the Recycling and gives with Audis Space Frame Technology good crash results .

Just because motorcycles might be more fuel efficient doesn't mean I think we should be forcing every American to drive one. You have to concede that currently there is some link between safety and vehicle size and besides, thats a consumer choice and not an issue for debate since they are the ultimate decider's. Additionally, the large point is how the CAFE standards have a larger effect on heavier autos and I'm not hearing any solution for that. In addition to safety concerns consumers need trucks, etc. for work reasons and can't simply buy smaller, lighter cars either. Until that gets figured out the impact of CAFE standards and other options should be considered further.