Ignoramus14774 wrote:
On 2009-04-17, Joseph Gwinn wrote:
Title says it all. Actually tons of metal involved. But too little for
safety.

http://online.wsj.com/article/SB123993371229527975.html

This is a shot in the coming fight about CAFE.

The Wall Street Journal, 17 April 2009.


So they say that minis fare badly in collision with heavier cars.
That's understandable.



No, they said teh *single car* death rate was twice the norm.



I am wondering about something? Does fuel efficiency of those tiny
cars come from then being small in dimensions, or light in weight?


Both, but at around town speeds, it's almost all about weight.

The stop and go aspect of city traffic means constantly accelerating
up to speed - then stopping. Then accelerating again.

Lighter weights (actually less mass) takes less energy to accelerate.


I suspect that it is mostly the former, due to improved wind
resistance and such.

Only at high speeds. 60 - 70 MPH on the highway verses 20 to 30 around town.

Google "aerodynamics of bluff bodies" for the ugly details.

If so, perhaps the tiny economy cars could be made heavier, but kept
to the same dimensions? Such as, perhaps, the frame could be made from
solid steel instead of tubing.

They need "crush space" to allow structure to dissipate energy while collapsing.
That's hard to come by when your feet reach the front bumper...


Richard