Tricky
Briefly immortal
Yeah, well there seems to be some disagreement about that.
US Dept. of Trans.
http://www-nrd.nhtsa.dot.gov/Pubs/808569.PDF
Effect of a 100-pound weight reduction for passenger cars
NHTSA estimates that a 100-pound reduction in the average weight of passenger cars, with
accompanying reductions (based on historical patterns) in other size parameters such as track width,
and in the absence of any compensatory improvements in safety technology, would have a
significant adverse impact on safety:
• Fatalities would increase by an estimated 302, which would be 1.1 percent over the current
level.
• Serious or moderate injuries (AIS 2-6) in nonrollover crashes would increase by 1,823,
which would be 1.6 percent over the current level
• Police-reported 'A' or TC' injuries, which are usually less serious than AIS 2-6 injuries, would
increase by 8,804 in nonrollover crashes, which would be 3.2 percent over the current level.
Did you read the whole thing?
So if all cars are smaller, net risk is reduced. And of course, this is assuming that all other things remain the same, i.e. no other safety improvements, of which there have been many since that fourteen-year-old study. Neither does it take into account health benefits, such as reduced pollution from smaller cars or economic benefits, such as reduced reliance on fossil fuels.Conclusion:
The results have a clear pattern: reducing a vehicle's weight increases net risk in collisions with substantially larger and stronger entities, reduces net risk in collisions with much smaller and more vulnerable entities, and has little effect on net fatalities in collisions with vehicles of about the same size (although nonfatal injuries increase).