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GM's goal is to cut weight by as much as 15 percent to reduce fuel consumption

General Motors (GM) is in the midst of developing an electric vehicle (EV) that can achieve 200 miles of battery-only range.

GM CEO Dan Akerson unveiled the project last week at the IHS CERAWeek energy conference broadcast on CNBC.com.

“There will be breakthroughs in battery technology, they’re on the horizon,” Akerson said. “We’re actually developing a car today which is really anathema to the way the auto industry works: We’re running a dual play on the technology to see which one will succeed. One will result in” a 100-mile range, “the other will be a 200-mile range.”

Akerson went on to say that fuel consumption can be reduced by 6.5 percent if the vehicle weight is cut by 10 percent. GM's goal is to cut weight by as much as 15 percent.


GM CEO Dan Akerson
 
Further, Akerson described GM's previous plans to put 500,000 green vehicles on the roads by 2017. It's doing this with its Chevrolet Volt, the new all-electric version of the Chevrolet Spark and a diesel version of the Chevrolet Cruze.

GM hopes to increase Volt sales by 20 percent this year alone.

“Everywhere you look there are opportunities to seize the energy high ground,” Akerson said. “Indeed, our leaders have been presented with an historic opportunity to create a national energy policy from a position of strength and abundance. The pillars of such a plan must include energy diversity, so we do not become dependent on any one fuel or energy source.”

Last week, Akerson called for a consumer-driven national energy policy where he'd like President Barack Obama to appoint a Blue Ribbon Commission (which would lead to the development a 30-year policy framework for energy security with progress reviews every five years).

Source: Bloomberg



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RE: Doubling down on dumb
By FiveTenths on 3/12/2013 2:00:42 PM , Rating: 2
What are you talking about?

5000lb car loses 15%, 750lbs, weighs 4250

4000lb car loses 15%, 600lbs, weighs 3400

Old difference was 1000 new difference is 850. The mass of the two is now closer so the risk to the smaller car should be less.


RE: Doubling down on dumb
By snhoj on 3/12/2013 7:36:10 PM , Rating: 2
It's really about relative weight rather than absolute weight difference.

Using combined momentum, Say both vehicles were travelling towards each other at 60mph. Say Q is the speed after impact. 9000lb x Q = 5000lb x 60mph + 4000lb x -60mph.
Transpose for Q = (5000x60-4000x60)/9000 = 6.67mph. Because the result is positive it is in the direction the 5000lb car was travelling in. So impact suffered by the 5000lb car is 60-6.67 = 53.33mph. Impact suffered by the 4000lb car is 60+6.67 = 66.67mph. 66.67/53.33=80% same as weight relativity of 5000/4000=80% also 4250/3400=80%.

Now kinetic energy = ½. M. V^2 so the total KE needing to be dissipated does decline by 15%.


RE: Doubling down on dumb
By FiveTenths on 3/12/2013 8:55:17 PM , Rating: 2
Thank you for the explanation.

Based on momentum then, you couldn't say the lighter weight vehicles are any more or less deadly than heavier vehicles. Even if you doubled the weight the now 8000lb vehicle would take more of an impact than the 10000lb vehicle.

So if the momentum is the same and the KE of the system is lower, why would making the vehicles lighter make them more deadly?


RE: Doubling down on dumb
By snhoj on 3/12/2013 10:23:26 PM , Rating: 2
quote:
Based on momentum then, you couldn't say the lighter weight vehicles are any more or less deadly than heavier vehicles.
What?

But that is exactly what momentum shows us assuming that greater impact velocities and higher Kinetic energy absorbtion in a lighter vehicle equals more deadly. By the way KE also follows the inverse weight relativity meaning the lighter vehicle also has to disipate a greater portion of the crash energy.


RE: Doubling down on dumb
By FiveTenths on 3/13/2013 12:12:30 PM , Rating: 2
I'm referring to the lighter pair of vehicles. My argument is not that the lighter of the two is safer, it's that reducing the weight of vehicles does not make them more deadly. You have just shown reducing weight equally leads to the same impact force distribution but less energy overall.

Vehicles like the f150 and Silverado weigh roughly 6400lbs almost any car is going to lose a collision with these trucks and they are the bestselling vehicles year over year so it's not an unlikely scenario. But by losing 15% the truck has almost 1000lbs less mass, so would it not actually be less deadly to whomever is hit by the truck?

And what about collisions with immovable objects? Or cars that are already lighter than the reduced weight vehicle?


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