If the other car was under heavy braking, it's front-end dips down and instead of a bumper-to-bumper collision, you have the rear-ending car go "under" the back

If the other car was under heavy braking, it's front-end dips down and instead of a bumper-to-bumper collision, you have the rear-ending car go "under" the back of the front car. Source: My old '81 Mustang got rear-ended at fairly high speed by a Civic and had no taillight damage. Lost my tailpipe but that was about all.