Honestly, I don't think the weight of the car matters too much in an accident with a bicycle or pedestrian. I was hit a few times by cars at low speed (10-20 km/h) while riding my motorcycle and the weight of the car did not matter, when I was rear ended if the car was 20% (300 kg) lighter it would still be 4 times the mass of (me + bike), so the impact would be similar. A car versus a pedestrian is almost identical if the car is 1000 kg or 2000 kg.
Yeah, I think the primary difference is the geometry - the SUVs and trucks present an almost flat surface and cause much more head and neck trauma - and in the visibility and controllability of the vehicle.
