Though at the mass ratios of car vs pedestrian/cyclists, the difference on the car side makes no significant effect. It doesn‘t really matter if the ratio is 1:10 in favor of the car or 1:20. The acceleration that the car will feel is negligible either way.
I neglected mass here, because I don't think it really makes much of a difference in the deadliness of the collision (car is always much heavier than cyclist).
One thing it would definitely affect tho is the time within which the car could brake, provided they react in time.
Newton's 3rd law, implies the more mass you have the less recoil you feel.
For example hitting a massive box will hurt a lot more than a light box, because light box will get some acceleration of its own vs massive box.