A more massive car has more energy to dissipate but also more structure (crumple zones) to apply this energy to. The net balance is not obvious me, either.
While most car accidents do not involve hitting walls, a lot involve hitting objects-other-than-cars (guard railings, trees, animals, etc.) where being heavy can be an advantage (because that excess energy that you have you dissipate into the object). As to pedestrians, the mass discrepancy is big enough to not matter—the consequences to the pedestrian of being hit by a 1-tonne car are the same as being hit by a 2-tonne car.
A more massive car has more energy to dissipate but also more structure (crumple zones) to apply this energy to. The net balance is not obvious me, either.
While most car accidents do not involve hitting walls, a lot involve hitting objects-other-than-cars (guard railings, trees, animals, etc.) where being heavy can be an advantage (because that excess energy that you have you dissipate into the object). As to pedestrians, the mass discrepancy is big enough to not matter—the consequences to the pedestrian of being hit by a 1-tonne car are the same as being hit by a 2-tonne car.
The 2-tonne car may be harder to stop or steer so that it doesn’t kill the pedestrian.
Being lighter is better in that case.
Why?