Fourth power of axle weight, apparently. So (weight/2)^4 for a car or SUV.
https://en.wikipedia.org/wiki/Fourth_power_law
Also, squishy humans really prefer to not be hit by heavier objects travelling at similar speeds.
https://en.wikipedia.org/wiki/Fourth_power_law
Also, squishy humans really prefer to not be hit by heavier objects travelling at similar speeds.