Pixels said:
But did they really test every seat, with every dummy? To me, it's kind of like the BundleMe makers saying they tested it with some seats and the seats still passed. It might be fine with some seats, but I honestly don't believe they tested them all (and new seats are always coming out) so they can't possibly say that it's safe with every seat.
No, they didn't test with every seat, but they tested with a lot. They went to BRU and Target and bought a bunch of seats (so new, popular ones, not old obscure things). They tested with child-sized dummies and with small adult female cadavers in booster seats.
They also manipulated the dummies to sit out of position in booster seats, including leaning and with the belt behind the child's back.
One of the cadaver tests might have been with the belt behind the back, too. I don't remember for sure, though.
Anyway, other than the SS1 lockoff breaking, there supposedly wasn't damage to any of the seats.
What DOES concern me is that supposedly Ford has stopped talking with car seat manufacturers? (Someone from here mentioned that.) If true, that surprises me because at Lifesavers they seemed to be working really hard to get info to the manufacturers. So that has me scratching my head a bit.
I'm not saying it's perfectly fine to use the belts in every--or any--situation. Obviously I don't have the kind of information or authority to say that. I would definitely use LATCH if possible, and would have to consider harnessed seats on a case-by-case basis.
For my OWN child, I would absolutely use them with a booster. Probably even if the booster manufacturer didn't allow it. The injury criteria from the female cadavers (in a seatbelt alone) was very impressive. (In a regular belt, it had multiple small rib fractures. In the inflatable belt, it had one microscopic fracture that they almost couldn't find.)