In the vast majority of cars, the parcel shelf is more a security item, too keep whatever is in the boot out of sight. Most parcel shelves are nowhere near strong enough to prevent something heavy coming forward, especially if the car rolls. Not sure about the Volvo, nor your Jeep, without seeing the shelf and this bar(?) you mention.

A very long time ago, I worked at a Saab dealer. When I started, the old classic shape 900 was still a current model. On the hatchback version of those, the parcel shelf was a rigid, cloth covered sheet of 1/2 inch plywood, so would be pretty effective at stopping stuff ending up in the cabin should you crash. When the new GM 900 came out, it had a fairly flimsy shelf of the type you find in most modern cars. It did however have a very sturdy removable bar which went across behind the top of the rear seat backs. As far as I remember, this had nothing to do with preventing stuff coming forward though, it was to provide extra stiffening to the body shell. Kind of like what a strut brace does except you could unclip it should you need to use all the available load space.

I reckon any parcel shelf robust enough to provide useful crash protection would be impossibly unwieldy as a parcel shelf, and would also need to be fixed in position. The only barrier capable of preventing loose objects flying too far in a crash might be something like a dog-guard behind the front seats ?

All my cars for the last 30 years, hatch or estate, have had removeable parcel shelves. In none of them was the shelf or it's fixings remotely robust enough to be any use if rear-ended. Neither would it keep luggage in the boot in the event of rapid deceleration.

We did fit 'dog guards' to the estates to contain luggage that went up to the roof.

My current Q2 has a rigid, removable shelf, but made of stuff that would give no protection.

But the previous Volvo V60 and the three Octavia estates before that had fabric covers which retracted into a (removable) metal framework. Maybe this framework, and the fixings at either end, might provide some protection, although I wouldn't have thought a great deal.

Just watching a car show, Motor Pickers' and the chap said the

rear parcel shelf in a Volvo estate was also a safety item in an even of a crash, IE

another car hits you in the back of your car, keeps occupants safer.

In my Jeep GC the bar is hefty and I often leave it out. Does this bar play a safety role in crashes in all cars? I know covering the items in the rear if you can does reduce the chance of items flying around in a crash but not this.

Only a safety item is someone hasn't stowed any items on it. Years ago, when my parents owned a Ford Escort, they always stowed umbrellas on the parcel shelf, as it had an 'indent' or cutout that seemed perfect for them.

Probably not a good idea if we'd had an accident.

I suspect they also help prevent the contents of the boot fyling into the rest of the car in a crash. One of the reasons a saloon is safer as it's fixed.