[camdat]

This assumes two vehicles of similar dimensions.

An aerodynamic 3,001lb vehicle would be much preferable to me than a 2,999lb flat-front. The physics imply only a portion of the heavier vehicles energy is imparted to me.

I don't make the comment to argue that weight isn't meaningful, but to say that "lethality" of a vehicle has many factors.

[pc86]

Yes it does, because we're talking about regulations that would cap the size of vehicle classes. You're not going to turn a 6,000lb F-150 into a 2,999lb truck, but you can shave 50 or 60 pounds off a vehicle.

All else being equal, lighter = less deadly. That's all I'm saying.