I'll post the conclusion for the light trucks weight reduction part (fatalities part, there is also non-serious injuries part in the paper) here as TL;DR for other people.
Reducing the mass of light trucks would significantly increase the fatality risk of their occupants in
collisions with objects and big trucks. But downsizing of light trucks would significantly reduce risk
to pedestrians, motorcyclists and, above all, passenger car occupants. There would be little effect
on rollovers because, historically, there has been little correlation between the mass of light trucks
and their rollover stability (width relative to center-of-gravity height). There would also be little
change in collisions between two light trucks, if both trucks are reduced in mass.
Even though the effect of mass reductions is statistically significant in four of the six types of
crashes, the net effect for all types of crashes combined is small, because some of the individual
effects are positive and others are negative. The benefits of truck downsizing for pedestrians and
car occupants could more than offset the fatality increase for light truck occupants. It is estimated
that a 100-pound reduction could result in a modest net savings of 40 lives, (0.26 percent of baseline
fatalities). However, this estimate is not statistically significant, the 2-sigma confidence bounds
range from a savings of 100 to an increase of 20 fatalities; the 3-sigma bounds range from a savings
of 130 to an increase of 50 fatalities. It is concluded that a reduction in the weight of light trucks
would have a negligible overall effect, but if there is an effect, it is most likely a modest reduction
of fatalities
I'll post the conclusion for the light trucks weight reduction part (fatalities part, there is also non-serious injuries part in the paper) here as TL;DR for other people.