interview > greene > greene 13

Greene 13 (2:57)
Topic(s): Car Culture / Efficiency / Future Transport
User Comments

Video Transcript

The argument that increasing fuel economy will decrease highway safety is simply not true. It hasn't been true in the past and there's no reason for it to be true in the future. Okay? What confuses people is that it's definitely true that if you run a huge vehicle into a small vehicle, the occupants of the smaller vehicle are at much greater risk than the occupants of the large vehicle. However, what I gain by buying a larger vehicle, heavier vehicle—not a larger vehicle actually. What I gain by buying a heavier vehicle, in terms of my car colliding with your car, you lose. So from a societal perspective, okay, this is essentially a zero-sum game. If I get a heavier car, I'm safer in a collision with you. You're less safe. Okay. What we know from the history of traffic fatalities in the US is that the increase in fuel economy we saw on the road has no correlation with traffic fatalities whatsoever, over the past 50 years.

We have the data now. Early on, there were some statistical analyses done, but only with the first 4 years of fuel economy improvements in new cars, not the— not— It takes 15 years for those fuel economy improvements to come all the way through the fleet. Now that we have the whole— all of the data, and we can look back to 1960, and say, you know, "Is there any correlation between fuel economy improvement and highway traffic fatalities?" Now we know there isn't any.

And in terms of the safety of individual vehicles and the role of mass, the weight of the vehicle, and the role of the size of the vehicle, the best evidence now shows that it would be good to maintain the size of the vehicles and take a little weight out. Because the, let's say, the consequences of a crash depend on the ability of the vehicle to slow down the rate of deceleration of the vehicle, and to slow down especially the rate of deceleration that the bodies inside experience. So keep them from colliding with the vehicle itself at a high speed, and slow down the maximum rate of deceleration in a crash. Having a little space, having some size to the vehicle, is helpful in that. Having extra mass for a given size is actually bad, because it means there's more energy that has to be absorbed, so it's harder for the structure to absorb that energy in a crash. And so what we understand now is that we would like to keep the size of the vehicles, but take some mass out. And that's good for fuel economy, to take some mass out.