In a theoretical rear-end car accident, would it be better to brake or not?

Not brake.

The energy of the offending car is going to be expended somewhere. You want it pushing you along, rather than crumpling your car.

Think of the extremes:
1) You accelerate and the car does not touch you.
2) You lock the brakes and get the full impact.

Depends on what’s in front of you. It’s an instant decision you have to make on the fly.

Depends on what’s in front of you

Oh yeah, I forgot that part. Rather important.

@jaytkay I’m really careful when I’m behind a motorcycle. Or a tractor trailer.

Mercedes has developed a system that detects an impending rear-end collision, then automatically sets the brakes hard. They say that not only does this avoid getting shoved into a dangerous situation ahead of you, but minimizes bodily injury due to rapid forward acceleration. Here’s their explanation.

They make a good point: it’s almost impossible to keep your foot on the brake pedal in a hard rear impact because you’re pressed a few inches into the seat back. Your foot is almost certain to come off the pedal.

Oh and also make sure you have the headrest set properly and you put your head back against it. I saw one car coming while I was behind a couple of cars turning left. I watched it all the way til his mouth dropped open just before he hit. That hurt even though I saw it coming.

@Adirondackwannabe I’m really careful when a tractor trailer is behind me. Lotsa momentum.

@jaytkay, I’m really nervous and careful when a driver talking on a cell phone is behind me!

I’m really careful when a train is behind me, but then if I was even more careful, I wouldn’t be in that situation in the first place! ;-p

@Brian1946 I’m wondering why the train is behind you, but if you drink I could see it.

Heh well….I was sandwiched a few years ago, shuttle van from a local car dealership pushed me into the car ahead of me. Yep, I agree with @thorninmud
I was stopped, foot on the brake and still got shoved, hard, into the car in front of me.
I also launched a giant cup of coffee all over my windshield, dash, seats and myself.

I was hopping mad! lol
Ironically I was on the way to a Dr. appt. so…got checked out, I was fine, and the dealership paid to detail my car as well as the body work.
That shuttle drive was not a happy guy. lol