Read only the abstract, but this sounds very plausible. Trying to replace my 2005 car, I am quite surprised current models of the same exterior size have much less interior space and many would not fit a young adult and 2 kids (my situation). Is there any engineering reason behind this? I would rather think there are commercial reasons.
Crumple zones and airbags take space. Roofs that can handle the car being flipped without deforming enough to hurt you need chunkier pillars (I really lament this, makes visibility a lot worse)
Mine has all the airbags a current car would have, so I do not believe this is the actual reason.
It has a lesser crash rating than modern cars, but the reason is there are structural elements that drivers legs could hit in a crash (https://www.euroncap.com/en/results/honda/cr-v/15568). Basically I thing the car is too stiff for Euroncap, but it does not make it less safe in my opinion. Crumple zones are sized for standardized impact tests.
I'm not sure why you're being so heavily down-voted since you're quite close to the truth.
Airbags mostly take up what on other cars was dead space behind trim.
Crumple zones #1 function is to buy time for the airbags to deploy between when the front of the vehicle starts slowing in a crash and when the cabin starts slowing. Think about it, if the cabin decelerated at the same rate as the front bumper the occupant would be half way to the steering wheel by the time the bag finished exploding and they'd get hit in the face with an exploding airbag. Crumple zones #2 is deceleration and is tuned for a specific speed of impact. They can be thought of as a single use coil spring without a damper. Too slow of an impact and they do little to nothing (no big deal because it's a slow impact). Too fast and you will blow right through your available travel and bottom out hard. Because the car manufacturers are not staffed by idiots they respond to incentives and tune their crumple zones to be most effective at crash absorption at the high end of the speeds they are tested at.
Most of the increase in "wall thickness" so to speak, of vehicles is from pillars and body structure that increases in width (to get more strength without adding too much material and weight). Then the trim is layered over that and that means you not only lose the space where the reinforcements are but over the whole vehicle.
I suspect the reality is improvements in structural design tools that permit the use of thinner metal for the chassis, provided that the upper body shell is less perforated with big holes to restore rigidity.
You see this with the ridiculously high belt lines that are "for safety" but have the convenient side effect of reducing the amount of glass.
No. They really don't. You can shove airbags in anywhere and the passenger cabin is not a crumple zone and is supposed to be rigid. The reduction in interior space comes from fatter structure in the pillars and the various other reinforcements (for that cabin rigidity). Then you add fatter interior trim (to hide fat wiring harnesses and reinforcements and thick sound deadening while still providing clean-ish lines) and the effect compounds.
One of the interesting things about the feedback we've gotten on the paper has been the number of people who report that this problem is a pain for them, even if it doesn't rise as far as stopping them having another child. To us, this makes it more likely that this pain (if real) is actually deterring some people who are at the margin.
My old 2005 Impala has less rear seat space than my 2014 Accord, so I'd swear the opposite of your experience. Maybe Hondas have more rear seat space than Chevys?
