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Study: No Trade-Off Between Higher Fuel Economy and Vehicle Safety

10 June 2007

Icct2
Sample safety risks of existing vehicles with high (green) and low (red) fuel economy. Click to enlarge.

A new study concludes that there is no trade-off required between higher fuel economy and vehicle safety.

The study, informed by an October 2006 experts workshop titled Simultaneously Improving Vehicle Safety and Fuel Economy through Improvements in Vehicle Design and Materials, concludes that manufacturers can use advanced materials to increase both fuel economy and safety without reducing a vehicle’s functionality. It also finds that reducing the weight and height of the heaviest SUVs and pickup trucks will simultaneously increase both their fuel economy and overall safety.

Icct1
Technology options for increasing fuel economy and/or safety. Click to enlarge.

The authors conclude that existing technology options can improve light-duty vehicle fuel economy by up to 50% over the next 10 years without reducing the weight or size of vehicles. Any extra cost associated with the auto-manufacturing changes would be more than offset by savings generated by more fuel-efficient vehicles.

A common argument against mandating significant increases in fuel economy is that such efficiency requirements would greatly decrease the safety of vehicles, thereby leading to increases in traffic fatalities.

The potential to improve the fuel economy of light-duty vehicles while also improving traffic safety is debated because of the claim that lighter vehicles are, and will forever remain, more dangerous for their occupants. The critical issue is whether these historical tendencies are intrinsic, or whether they continue to change over time with new designs, testing, and sound regulations. The reality is that these relationships are not intrinsic to motor vehicles. Rather, the linkages among fuel economy, vehicle size, weight, and safety are manageable and are more a function of smart vehicle design than any other single factor.

Sipping Fuel and Saving Lives: Increasing Fuel Economy without Sacrificing Safety

The authors of the study, Sipping Fuel and Saving Lives: Increasing Fuel Economy without Sacrificing Safety, are Deborah Gordon, a transportation policy consultant; David L. Greene, a fuel-economy policy expert; Marc H. Ross, emeritus professor of physics at the University of Michigan; and Tom P. Wenzel, of the Lawrence Berkeley National Laboratory.

The study’s authors reviewed a decade’s worth of recent research in the field and concluded:

  • Most technologies to increase fuel economy do not affect safety; most technologies to increase safety do not affect fuel economy.

    The inherent relationship between vehicle safety and fuel economy has long been the subject of discussion. The many technologies available to improve vehicle fuel economy (particularly those that do not involve weight reduction) have no impact on vehicle safety. Those approaches that strategically reduce vehicle weight (using new lightweight materials to reduce weight while holding vehicle size constant and reducing the weight of the heaviest trucks and SUVs to make them less aggressive) also improve fuel economy while maintaining, and perhaps even improving, vehicle safety.

  • Reducing car mass while improving vehicle structure, using advanced materials and designs, can simultaneously increase fuel economy and safety.

  • Reducing the weight and improving the structure of truck-based SUVs and pickups can increase their fuel economy and improve the safety of all vehicles on the road.

The study recommends that policymakers:

  • Set fuel economy and safety performance goals at cost-effective levels, and allow adequate time for phase-in of vehicle redesigns.

  • Develop short-term goals that use existing technological potential and long-term goals to spur continued innovation.

  • Apply the same fuel economy and safety standards consistently to all vehicle types (cars, SUVs, and pickups).

  • Encourage driver behavior that improves fuel economy or safety—e.g. seat belt use or reduced driving speeds.

The report was presented by the International Council on Clean Transportation (ICCT). The William and Flora Hewlett Foundation convened the experts meeting that led to the report.

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June 10, 2007 in Fuel Efficiency, Policy | Permalink | Comments (38) | TrackBack (0)

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Comments

Too bad many SUV buyers don't know the best kept secret by auto company salesmen is a high CG is directly proportional to the safety risk.

The effect: Once your SUV gets sideways, you roll.

In general suv buyers fall into two groups.

Those who equate size with safety.

And those who feel others are more a safety risk then thier own driving. This second group is very big around high 18 wheeler roads...

This issue seems to be a purely N. American phenomenon whereas European and Asian markets understand that the weight of a car has absolutely nothing to do with safety, in the US having a heavier vehicle is flaunted as being more safe.

As we all learned in school, force = mass * acceleration, if you have a big ass heavy car, it is going to take longer to stop, if you hit a wall, tree, lamp-post you will go further into the wall than you would with a lighter car that will probably change direction faster in the first place, thus avoiding the wall. (I read a report that said hitting other stuff on the road is 90% of situations, not involving other vehicles)

The notion of hitting another vehicle head on is a very rare occurence. Furthermore a british show called fifth gear highlihted the fact that most SUV's are built on a ladder frame and are not monocoque so in the event of an accident there is less structure to absorb the impact, thus the engine and everything else gets pushed into your legs and chest. They demonstrated by crashing a large SUV LandRover Discovery LR3 with a Renault Espace (think Mazda 5) which is monocoque. The occupants of the SUV came off a lot worse.

There is a video of this on google/youtube:

http://www.youtube.com/watch?v=GEBC9PbjPv4

Remember that in the US, unlike every other vehicle market, crash certification still has to be passed without any seat belts.

Car makers have no choice but to add a lot of heavy steel to improve passive safety and then, increase engine power to maintain vehicle performance. That increases weight yet further and, ups the specs on engine mounts, suspension and noise dampening. Needless to say, all of this reduces fuel economy.

If US lawmakers were serious about maintaining vehicle safety while improving fuel economy, the first thing they should do is mandate wearing seat belts fore and aft and, permit carmakers to perform crash tests accordingly.

Second, they should permit car makers to activate all relevant active safety features, e.g. radar, infrared detectors, pre-tighteners for the belts, peel-away belt mounts, isofix child seat attachments etc.

It's no use arguing that all of this would put models by US manufacturers at a competitive disadvantage: GM and Ford at least both have European subsidiaries producing decent mid-sized cars that get fairly good fuel economy, even on gasoline. The main reason they cannot easily introduce these to the US market is that crash test regulations entail major structural modifications.

Good link, I would like to see my local news station play that video, or do an experiment like that. However I would like to see a small car, like an accent, or a yaris go up against the Land Rover.

"If US lawmakers were serious about maintaining vehicle safety while improving fuel economy, the first thing they should do is mandate wearing seat belts fore and aft and, permit carmakers to perform crash tests accordingly."

Yes, good point. I didn't know until a few days ago that US crash-testing considered unbelted occupants. I must say I have very little concern for those who refuse to belt themselves in.

Rafael.

I did not know that they did not use seat belts during the crash tests. That seems insane. I wonder if congress understands that. Outrageous.

I still think it is possible, however, that the U.S. automakers like the status quo. If we adopted European safety standards, there would be a flood of imports. More often than not, the cars with good gas mileage on this web site are only made in Europe.

I think part of it maybe that the type of people that drive SUV and trucks might be less likely to be competent drivers.

Any proof of that Ben?

James, get off it. READ. He said "I think..." Hence it is his opinion. Rule #1, avoid being a douche by READING the post.

This is intrinsically counter intuitive to any Engineer.

A vehicle that can accelerate to match speeds on a freeway ramp or can accelerate to pass a slower vehicle is safer, as its exposure in time to such exposed situations is less. A vehicle so equipped has a higher out put prime mover. That wii consume more fuel outright and because its larger prime mover, weight will be greater, as well. Once again heavier means poorer fuel economy.

A vehicle equipped with ABS ant-skid braking control will weigh more than a vehicle without such equipment. Once again heavier means poorer fuel economy.

A vehicle equipped wirth stability control anti skid enahnced steering control will weigh more than a vehicle not so equipped. Once again heavier means poorer fuel economy.

A vehicle equipped with safety belts and airbags weighs more than a vehicle not similarly equipped. Once again heavier means poorer fuel economy.

A vehicle with engineered crumple zones and side impact protection body structure will weight more than a vehiclee nost so equipped. Once again heavier means poorer fuel economy.

How many more simple engineering statements must I make to show that this report is .... pure drivel.

Booker, I have warned other posters previously, and now it looks like it is your turn. If you can't make non-confrontational posts, then don't post at all. I suggest you take a few days off to think about it.

If you post this type of nonsense again, I will inform Mike and you will be banned.


There are many safe car designs that if they were constructed of the proper materials - Carbon Fiber, Kevlar, Spectra, Expanded Polypropylene, etc. - would be much safer in a crash that existing vehicles.

There are very few smart, creative engineers working for car companies. The really good ones won't put up with the BS from the suits.

I'm sorry, Booker; but, you're just dead wrong. And if you ARE an engineer, you'll take a look at the evidence for what this study suggests is true.

http://www.rmi.org/images/PDFs/Transportation/T02-10_DsnManuAdvComp.pdf

http://www.rmi.org/images/PDFs/Transportation/T01-22_NextExit.pdf

All the best!

Sorry, that last was meant for Stan Peterson.

again with the rampant missinformation. 10,000 lb suv head on with a 3,000 car = dead economy car driver and brused leg in SUV driver.
The safest vehicle on the road is the Chevy Astro Van. Lowest deaths per million miles driven. Why? its very heavy and very balanced like a tank.

Stan - "How many more simple engineering statements must I make to show that this report is .... pure drivel."

So what you are saying is that a properly equipped car must be heavy and have poor fuel economy?

How about the Honda Civic:
http://www.honda.com.au/wps/wcm/connect/Honda.com.au/Home/Showroom/Civic/Specifications/

It has all the things that you mentioned and has good fuel economy and performance.
http://tinyurl.com/3d2w3t

There are many many cars that combine all the features that you mentioned it is just the American cars are not well represented. Perhaps it is the reason the GM is not number 1 anymore. When engineers such as yourself say that you cannot do it when it is obvious that other engineers can innovate and achieve the things that you say cannot be done then that is very sad for the US manufacturing industry.

James,

Aside for the drunken red-necks around where I live, no.

Ben, I'd wager the average suv driver is a lot more educated than you are.

Well... lets put it this way...

How many of us plan to wait as long as possible after this stuff kicks in to triple check actual crash data to see if the car makers screw the pooch on safety while ramping fuel econ up?

Right now I dont trust anyone.

Ben, I'd wager the average suv driver is a lot more educated than you are.

Marginally increasing fuel economy without sacrificing safety, when the fleet is getting safer all the time. Should we just sit back, and let the auto factories continue to control the public's desire for fashionable transportation through their hypnotizing promotion of constantly heavier and heavier vehicles? The ones that make a triple or quadruple profit for the manufacturer? Fasion=profit.

We all know that heavy consumer vehicles are unsustainable, that they're an inherent safety hazard when they get a blow-out, or when they try to turn on a slippery surface. We know they have a much higher mass polar moment. They spin and flip.

What could we add in terms of economy? That's iterated daily in this blog. What could we add in terms of safety while we're at it? We desperately need standards for braking performance, with the vehicle going into limp-mode when it is unsafe to drive. We need mandated ABS, ESP, bumper standards for all vehicles, all-point crash standards, tip-up standards, roof standards, lighting standards, tire blow-out standards, suspension joint standards, headrest standards, headliner standard, and glass and mirror standards. There's a start. We could have all of this for the cost of a sunroof.

I'm in favor of keeping high center-gravity SUVs.
It's the best way of "culling the herd".

There's an easy way to test Ben's idea, or a more generalized version of it. Look up the stats on specific makes and models, and then look for the identical car "badged" for the various Divisions at US automakers.

For what it's worth, I remember in the old days that near-identical 1980s VW Rabbits and Siroccos had very different accident rates. Aspiring "sport drivers" bought the Siroccos and a higher percentage crashed them than did the moms who bought rabbits.

Or as my Dad like to remind me when I was growing up, when the Porsche was introduced in America it was the best handling car on the road ... and that year there were more "single car accidents" in those than in any other.

Surely some particular SUVs (as some small cars) are stupidity magnets.

Several years ago I was drifting down the hill at 15 mph, slipping on Black Ice when a SUV breezed by me.

Like about 9 out of 10 us would think, "A--hole!" popped to mind.

Not to worry ... Another SUV coming much too fast from the other way, lost it and did two full flips in the air before stopping on his wheels. "Lucky SOB!" I thought.

Just then the dude that breezed by me lost it and Tee-boned him.

I giggled all the rest of the way home.

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